/*
 * Copyright (C) 2004 Zack Rusin <zack@kde.org>
 * Copyright (C) 2004-2017 Apple Inc. All rights reserved.
 * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
 * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
 * Copyright (C) 2011 Sencha, Inc. All rights reserved.
 * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301  USA
 */

#include "config.h"
#include "CSSComputedStyleDeclaration.h"

#include "BasicShapeFunctions.h"
#include "CSSAnimationController.h"
#include "CSSAnimationTriggerScrollValue.h"
#include "CSSAspectRatioValue.h"
#include "CSSBasicShapes.h"
#include "CSSBorderImage.h"
#include "CSSBorderImageSliceValue.h"
#include "CSSFontFeatureValue.h"
#include "CSSFontStyleValue.h"
#include "CSSFontValue.h"
#include "CSSFontVariationValue.h"
#include "CSSFunctionValue.h"
#include "CSSLineBoxContainValue.h"
#include "CSSPrimitiveValue.h"
#include "CSSPrimitiveValueMappings.h"
#include "CSSPropertyNames.h"
#include "CSSPropertyParser.h"
#include "CSSReflectValue.h"
#include "CSSSelector.h"
#include "CSSShadowValue.h"
#include "CSSTimingFunctionValue.h"
#include "CSSValueList.h"
#include "CSSValuePool.h"
#include "ComposedTreeAncestorIterator.h"
#include "ContentData.h"
#include "CursorList.h"
#include "DeprecatedCSSOMValue.h"
#include "Document.h"
#include "DocumentTimeline.h"
#include "FontCascade.h"
#include "FontSelectionValueInlines.h"
#include "FontTaggedSettings.h"
#include "NodeRenderStyle.h"
#include "Pair.h"
#include "Rect.h"
#include "RenderBlock.h"
#include "RenderBox.h"
#include "RenderInline.h"
#include "RenderStyle.h"
#include "RuntimeEnabledFeatures.h"
#include "SVGElement.h"
#include "Settings.h"
#include "ShapeValue.h"
#include "StyleProperties.h"
#include "StylePropertyShorthand.h"
#include "StylePropertyShorthandFunctions.h"
#include "StyleResolver.h"
#include "StyleScope.h"
#include "StyleScrollSnapPoints.h"
#include "WebKitFontFamilyNames.h"
#include "WillChangeData.h"
#include <wtf/NeverDestroyed.h>
#include <wtf/text/StringBuilder.h>

#include "CSSGridLineNamesValue.h"
#include "CSSGridTemplateAreasValue.h"
#include "RenderGrid.h"

#if ENABLE(DASHBOARD_SUPPORT)
#include "DashboardRegion.h"
#endif

#if ENABLE(CSS_ANIMATIONS_LEVEL_2)
#include "AnimationTrigger.h"
#endif

namespace WebCore {

// List of all properties we know how to compute, omitting shorthands.
static const CSSPropertyID computedProperties[] = {
    CSSPropertyAlt,
    CSSPropertyAnimationDelay,
    CSSPropertyAnimationDirection,
    CSSPropertyAnimationDuration,
    CSSPropertyAnimationFillMode,
    CSSPropertyAnimationIterationCount,
    CSSPropertyAnimationName,
    CSSPropertyAnimationPlayState,
    CSSPropertyAnimationTimingFunction,
    CSSPropertyBackgroundAttachment,
    CSSPropertyBackgroundBlendMode,
    CSSPropertyBackgroundClip,
    CSSPropertyBackgroundColor,
    CSSPropertyBackgroundImage,
    CSSPropertyBackgroundOrigin,
    CSSPropertyBackgroundPosition, // more-specific background-position-x/y are non-standard
    CSSPropertyBackgroundRepeat,
    CSSPropertyBackgroundSize,
    CSSPropertyBorderBottomColor,
    CSSPropertyBorderBottomLeftRadius,
    CSSPropertyBorderBottomRightRadius,
    CSSPropertyBorderBottomStyle,
    CSSPropertyBorderBottomWidth,
    CSSPropertyBorderCollapse,
    CSSPropertyBorderImageOutset,
    CSSPropertyBorderImageRepeat,
    CSSPropertyBorderImageSlice,
    CSSPropertyBorderImageSource,
    CSSPropertyBorderImageWidth,
    CSSPropertyBorderLeftColor,
    CSSPropertyBorderLeftStyle,
    CSSPropertyBorderLeftWidth,
    CSSPropertyBorderRightColor,
    CSSPropertyBorderRightStyle,
    CSSPropertyBorderRightWidth,
    CSSPropertyBorderTopColor,
    CSSPropertyBorderTopLeftRadius,
    CSSPropertyBorderTopRightRadius,
    CSSPropertyBorderTopStyle,
    CSSPropertyBorderTopWidth,
    CSSPropertyBottom,
    CSSPropertyBoxShadow,
    CSSPropertyBoxSizing,
    CSSPropertyCaptionSide,
    CSSPropertyCaretColor,
    CSSPropertyClear,
    CSSPropertyClip,
    CSSPropertyColor,
    CSSPropertyAppleColorFilter,
    CSSPropertyCounterIncrement,
    CSSPropertyCounterReset,
    CSSPropertyContent,
    CSSPropertyCursor,
    CSSPropertyDirection,
    CSSPropertyDisplay,
    CSSPropertyEmptyCells,
    CSSPropertyFloat,
    CSSPropertyFontFamily,
    CSSPropertyFontSize,
    CSSPropertyFontStretch,
    CSSPropertyFontStyle,
    CSSPropertyFontSynthesis,
    CSSPropertyFontVariant,
    CSSPropertyFontWeight,
#if ENABLE(VARIATION_FONTS)
    CSSPropertyFontOpticalSizing,
#endif
    CSSPropertyHangingPunctuation,
    CSSPropertyHeight,
#if ENABLE(CSS_IMAGE_ORIENTATION)
    CSSPropertyImageOrientation,
#endif
    CSSPropertyImageRendering,
#if ENABLE(CSS_IMAGE_RESOLUTION)
    CSSPropertyImageResolution,
#endif
    CSSPropertyLeft,
    CSSPropertyLetterSpacing,
    CSSPropertyLineHeight,
    CSSPropertyListStyleImage,
    CSSPropertyListStylePosition,
    CSSPropertyListStyleType,
    CSSPropertyMarginBottom,
    CSSPropertyMarginLeft,
    CSSPropertyMarginRight,
    CSSPropertyMarginTop,
    CSSPropertyMaxHeight,
    CSSPropertyMaxWidth,
    CSSPropertyMinHeight,
    CSSPropertyMinWidth,
    CSSPropertyObjectFit,
    CSSPropertyObjectPosition,
    CSSPropertyOpacity,
    CSSPropertyOrphans,
    CSSPropertyOutlineColor,
    CSSPropertyOutlineOffset,
    CSSPropertyOutlineStyle,
    CSSPropertyOutlineWidth,
    CSSPropertyOverflowWrap,
    CSSPropertyOverflowX,
    CSSPropertyOverflowY,
    CSSPropertyPaddingBottom,
    CSSPropertyPaddingLeft,
    CSSPropertyPaddingRight,
    CSSPropertyPaddingTop,
    CSSPropertyPageBreakAfter,
    CSSPropertyPageBreakBefore,
    CSSPropertyPageBreakInside,
    CSSPropertyPointerEvents,
    CSSPropertyPosition,
    CSSPropertyResize,
    CSSPropertyRight,
    CSSPropertySpeakAs,
    CSSPropertyTableLayout,
    CSSPropertyTabSize,
    CSSPropertyTextAlign,
    CSSPropertyTextDecoration,
#if ENABLE(CSS3_TEXT)
    CSSPropertyWebkitTextAlignLast,
    CSSPropertyWebkitTextJustify,
#endif // CSS3_TEXT
    CSSPropertyWebkitTextDecorationLine,
    CSSPropertyWebkitTextDecorationStyle,
    CSSPropertyWebkitTextDecorationColor,
    CSSPropertyWebkitTextDecorationSkip,
    CSSPropertyWebkitTextUnderlinePosition,
    CSSPropertyTextIndent,
    CSSPropertyTextRendering,
    CSSPropertyTextShadow,
    CSSPropertyTextOverflow,
    CSSPropertyTextTransform,
    CSSPropertyTop,
    CSSPropertyTransform,
    CSSPropertyTransformBox,
    CSSPropertyTransformOrigin,
    CSSPropertyTransformStyle,
    CSSPropertyTransitionDelay,
    CSSPropertyTransitionDuration,
    CSSPropertyTransitionProperty,
    CSSPropertyTransitionTimingFunction,
    CSSPropertyUnicodeBidi,
    CSSPropertyVerticalAlign,
    CSSPropertyVisibility,
    CSSPropertyWhiteSpace,
    CSSPropertyWidows,
    CSSPropertyWidth,
    CSSPropertyWillChange,
    CSSPropertyWordBreak,
    CSSPropertyWordSpacing,
    CSSPropertyWordWrap,
#if ENABLE(CSS_SCROLL_SNAP)
    CSSPropertyScrollSnapMargin,
    CSSPropertyScrollSnapMarginLeft,
    CSSPropertyScrollSnapMarginTop,
    CSSPropertyScrollSnapMarginRight,
    CSSPropertyScrollSnapMarginBottom,
    CSSPropertyScrollPadding,
    CSSPropertyScrollPaddingLeft,
    CSSPropertyScrollPaddingTop,
    CSSPropertyScrollPaddingRight,
    CSSPropertyScrollPaddingBottom,
    CSSPropertyScrollSnapType,
    CSSPropertyScrollSnapAlign,
#endif
    CSSPropertyZIndex,
    CSSPropertyZoom,
#if ENABLE(CSS_ANIMATIONS_LEVEL_2)
    CSSPropertyWebkitAnimationTrigger,
#endif
    CSSPropertyWebkitAppearance,
    CSSPropertyWebkitBackfaceVisibility,
    CSSPropertyWebkitBackgroundClip,
    CSSPropertyWebkitBackgroundComposite,
    CSSPropertyWebkitBackgroundOrigin,
    CSSPropertyWebkitBackgroundSize,
#if ENABLE(CSS_COMPOSITING)
    CSSPropertyMixBlendMode,
    CSSPropertyIsolation,
#endif
    CSSPropertyWebkitBorderFit,
    CSSPropertyWebkitBorderHorizontalSpacing,
    CSSPropertyWebkitBorderImage,
    CSSPropertyWebkitBorderVerticalSpacing,
    CSSPropertyWebkitBoxAlign,
#if ENABLE(CSS_BOX_DECORATION_BREAK)
    CSSPropertyWebkitBoxDecorationBreak,
#endif
    CSSPropertyWebkitBoxDirection,
    CSSPropertyWebkitBoxFlex,
    CSSPropertyWebkitBoxFlexGroup,
    CSSPropertyWebkitBoxLines,
    CSSPropertyWebkitBoxOrdinalGroup,
    CSSPropertyWebkitBoxOrient,
    CSSPropertyWebkitBoxPack,
    CSSPropertyWebkitBoxReflect,
    CSSPropertyWebkitBoxShadow,
    CSSPropertyWebkitClipPath,
    CSSPropertyWebkitColumnBreakAfter,
    CSSPropertyWebkitColumnBreakBefore,
    CSSPropertyWebkitColumnBreakInside,
    CSSPropertyWebkitColumnAxis,
    CSSPropertyColumnCount,
    CSSPropertyColumnFill,
    CSSPropertyColumnGap,
    CSSPropertyRowGap,
    CSSPropertyWebkitColumnProgression,
    CSSPropertyColumnRuleColor,
    CSSPropertyColumnRuleStyle,
    CSSPropertyColumnRuleWidth,
    CSSPropertyColumnSpan,
    CSSPropertyColumnWidth,
#if ENABLE(CURSOR_VISIBILITY)
    CSSPropertyWebkitCursorVisibility,
#endif
#if ENABLE(DASHBOARD_SUPPORT)
    CSSPropertyWebkitDashboardRegion,
#endif
    CSSPropertyAlignContent,
    CSSPropertyAlignItems,
    CSSPropertyAlignSelf,
    CSSPropertyFilter,
    CSSPropertyFlexBasis,
    CSSPropertyFlexDirection,
    CSSPropertyFlexFlow,
    CSSPropertyFlexGrow,
    CSSPropertyFlexShrink,
    CSSPropertyFlexWrap,
    CSSPropertyJustifyContent,
    CSSPropertyJustifySelf,
    CSSPropertyJustifyItems,
    CSSPropertyPlaceContent,
    CSSPropertyPlaceItems,
    CSSPropertyPlaceSelf,
#if ENABLE(FILTERS_LEVEL_2)
    CSSPropertyWebkitBackdropFilter,
#endif
    CSSPropertyWebkitFontKerning,
    CSSPropertyWebkitFontSmoothing,
    CSSPropertyFontVariantLigatures,
    CSSPropertyFontVariantPosition,
    CSSPropertyFontVariantCaps,
    CSSPropertyFontVariantNumeric,
    CSSPropertyFontVariantAlternates,
    CSSPropertyFontVariantEastAsian,
#if ENABLE(VARIATION_FONTS)
    CSSPropertyFontVariationSettings,
#endif
    CSSPropertyGridAutoColumns,
    CSSPropertyGridAutoFlow,
    CSSPropertyGridAutoRows,
    CSSPropertyGridColumnEnd,
    CSSPropertyGridColumnStart,
    CSSPropertyGridTemplateAreas,
    CSSPropertyGridTemplateColumns,
    CSSPropertyGridTemplateRows,
    CSSPropertyGridRowEnd,
    CSSPropertyGridRowStart,
    CSSPropertyWebkitHyphenateCharacter,
    CSSPropertyWebkitHyphenateLimitAfter,
    CSSPropertyWebkitHyphenateLimitBefore,
    CSSPropertyWebkitHyphenateLimitLines,
    CSSPropertyWebkitHyphens,
    CSSPropertyWebkitInitialLetter,
    CSSPropertyWebkitLineAlign,
    CSSPropertyWebkitLineBoxContain,
    CSSPropertyLineBreak,
    CSSPropertyWebkitLineClamp,
    CSSPropertyWebkitLineGrid,
    CSSPropertyWebkitLineSnap,
    CSSPropertyWebkitLocale,
    CSSPropertyWebkitMarginBeforeCollapse,
    CSSPropertyWebkitMarginAfterCollapse,
    CSSPropertyWebkitMarqueeDirection,
    CSSPropertyWebkitMarqueeIncrement,
    CSSPropertyWebkitMarqueeRepetition,
    CSSPropertyWebkitMarqueeStyle,
    CSSPropertyWebkitMaskBoxImage,
    CSSPropertyWebkitMaskBoxImageOutset,
    CSSPropertyWebkitMaskBoxImageRepeat,
    CSSPropertyWebkitMaskBoxImageSlice,
    CSSPropertyWebkitMaskBoxImageSource,
    CSSPropertyWebkitMaskBoxImageWidth,
    CSSPropertyWebkitMaskClip,
    CSSPropertyWebkitMaskComposite,
    CSSPropertyWebkitMaskImage,
    CSSPropertyWebkitMaskOrigin,
    CSSPropertyWebkitMaskPosition,
    CSSPropertyWebkitMaskRepeat,
    CSSPropertyWebkitMaskSize,
    CSSPropertyWebkitMaskSourceType,
    CSSPropertyWebkitNbspMode,
    CSSPropertyOrder,
#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
    CSSPropertyWebkitOverflowScrolling,
#endif
    CSSPropertyPerspective,
    CSSPropertyPerspectiveOrigin,
    CSSPropertyWebkitPrintColorAdjust,
    CSSPropertyWebkitRtlOrdering,
#if PLATFORM(IOS)
    CSSPropertyWebkitTouchCallout,
#endif
#if ENABLE(TOUCH_EVENTS)
    CSSPropertyWebkitTapHighlightColor,
#endif
    CSSPropertyWebkitTextCombine,
    CSSPropertyWebkitTextDecorationsInEffect,
    CSSPropertyWebkitTextEmphasisColor,
    CSSPropertyWebkitTextEmphasisPosition,
    CSSPropertyWebkitTextEmphasisStyle,
    CSSPropertyWebkitTextFillColor,
    CSSPropertyWebkitTextOrientation,
    CSSPropertyWebkitTextSecurity,
#if ENABLE(TEXT_AUTOSIZING)
    CSSPropertyWebkitTextSizeAdjust,
#endif
    CSSPropertyWebkitTextStrokeColor,
    CSSPropertyWebkitTextStrokeWidth,
    CSSPropertyWebkitTextZoom,
    CSSPropertyWebkitTransformStyle,
    CSSPropertyWebkitUserDrag,
    CSSPropertyWebkitUserModify,
    CSSPropertyWebkitUserSelect,
    CSSPropertyShapeImageThreshold,
    CSSPropertyShapeMargin,
    CSSPropertyShapeOutside,
    CSSPropertyShapeRendering,
    CSSPropertyBufferedRendering,
    CSSPropertyClipPath,
    CSSPropertyClipRule,
    CSSPropertyCx,
    CSSPropertyCy,
    CSSPropertyMask,
    CSSPropertyMaskType,
    CSSPropertyFloodColor,
    CSSPropertyFloodOpacity,
    CSSPropertyLightingColor,
    CSSPropertyStopColor,
    CSSPropertyStopOpacity,
    CSSPropertyColorInterpolation,
    CSSPropertyColorInterpolationFilters,
    CSSPropertyColorRendering,
    CSSPropertyFill,
    CSSPropertyFillOpacity,
    CSSPropertyFillRule,
    CSSPropertyMarkerEnd,
    CSSPropertyMarkerMid,
    CSSPropertyMarkerStart,
    CSSPropertyPaintOrder,
    CSSPropertyR,
    CSSPropertyRx,
    CSSPropertyRy,
    CSSPropertyStroke,
    CSSPropertyStrokeColor,
    CSSPropertyStrokeDasharray,
    CSSPropertyStrokeDashoffset,
    CSSPropertyStrokeLinecap,
    CSSPropertyStrokeLinejoin,
    CSSPropertyStrokeMiterlimit,
    CSSPropertyStrokeOpacity,
    CSSPropertyStrokeWidth,
    CSSPropertyAlignmentBaseline,
    CSSPropertyBaselineShift,
    CSSPropertyDominantBaseline,
    CSSPropertyKerning,
    CSSPropertyTextAnchor,
    CSSPropertyWritingMode,
    CSSPropertyGlyphOrientationHorizontal,
    CSSPropertyGlyphOrientationVertical,
    CSSPropertyWebkitSvgShadow,
    CSSPropertyVectorEffect,
    CSSPropertyX,
    CSSPropertyY
};

const unsigned numComputedProperties = WTF_ARRAY_LENGTH(computedProperties);

static CSSValueID valueForRepeatRule(int rule)
{
    switch (rule) {
        case RepeatImageRule:
            return CSSValueRepeat;
        case RoundImageRule:
            return CSSValueRound;
        case SpaceImageRule:
            return CSSValueSpace;
        default:
            return CSSValueStretch;
    }
}

static Ref<CSSPrimitiveValue> valueForImageSliceSide(const Length& length)
{
    // These values can be percentages, numbers, or while an animation of mixed types is in progress,
    // a calculation that combines a percentage and a number.
    if (length.isPercent())
        return CSSValuePool::singleton().createValue(length.percent(), CSSPrimitiveValue::CSS_PERCENTAGE);
    if (length.isFixed())
        return CSSValuePool::singleton().createValue(length.value(), CSSPrimitiveValue::CSS_NUMBER);

    // Calculating the actual length currently in use would require most of the code from RenderBoxModelObject::paintNinePieceImage.
    // And even if we could do that, it's not clear if that's exactly what we'd want during animation.
    // FIXME: For now, just return 0.
    ASSERT(length.isCalculated());
    return CSSValuePool::singleton().createValue(0, CSSPrimitiveValue::CSS_NUMBER);
}

static Ref<CSSBorderImageSliceValue> valueForNinePieceImageSlice(const NinePieceImage& image)
{
    auto& slices = image.imageSlices();

    RefPtr<CSSPrimitiveValue> top = valueForImageSliceSide(slices.top());

    RefPtr<CSSPrimitiveValue> right;
    RefPtr<CSSPrimitiveValue> bottom;
    RefPtr<CSSPrimitiveValue> left;

    if (slices.right() == slices.top() && slices.bottom() == slices.top() && slices.left() == slices.top()) {
        right = top;
        bottom = top;
        left = top;
    } else {
        right = valueForImageSliceSide(slices.right());

        if (slices.bottom() == slices.top() && slices.right() == slices.left()) {
            bottom = top;
            left = right;
        } else {
            bottom = valueForImageSliceSide(slices.bottom());

            if (slices.left() == slices.right())
                left = right;
            else
                left = valueForImageSliceSide(slices.left());
        }
    }

    auto quad = Quad::create();
    quad->setTop(WTFMove(top));
    quad->setRight(WTFMove(right));
    quad->setBottom(WTFMove(bottom));
    quad->setLeft(WTFMove(left));

    return CSSBorderImageSliceValue::create(CSSValuePool::singleton().createValue(WTFMove(quad)), image.fill());
}

static Ref<CSSPrimitiveValue> valueForNinePieceImageQuad(const LengthBox& box)
{
    RefPtr<CSSPrimitiveValue> top;
    RefPtr<CSSPrimitiveValue> right;
    RefPtr<CSSPrimitiveValue> bottom;
    RefPtr<CSSPrimitiveValue> left;

    auto& cssValuePool = CSSValuePool::singleton();

    if (box.top().isRelative())
        top = cssValuePool.createValue(box.top().value(), CSSPrimitiveValue::CSS_NUMBER);
    else
        top = cssValuePool.createValue(box.top());

    if (box.right() == box.top() && box.bottom() == box.top() && box.left() == box.top()) {
        right = top;
        bottom = top;
        left = top;
    } else {
        if (box.right().isRelative())
            right = cssValuePool.createValue(box.right().value(), CSSPrimitiveValue::CSS_NUMBER);
        else
            right = cssValuePool.createValue(box.right());

        if (box.bottom() == box.top() && box.right() == box.left()) {
            bottom = top;
            left = right;
        } else {
            if (box.bottom().isRelative())
                bottom = cssValuePool.createValue(box.bottom().value(), CSSPrimitiveValue::CSS_NUMBER);
            else
                bottom = cssValuePool.createValue(box.bottom());

            if (box.left() == box.right())
                left = right;
            else {
                if (box.left().isRelative())
                    left = cssValuePool.createValue(box.left().value(), CSSPrimitiveValue::CSS_NUMBER);
                else
                    left = cssValuePool.createValue(box.left());
            }
        }
    }

    auto quad = Quad::create();
    quad->setTop(WTFMove(top));
    quad->setRight(WTFMove(right));
    quad->setBottom(WTFMove(bottom));
    quad->setLeft(WTFMove(left));

    return cssValuePool.createValue(WTFMove(quad));
}

static Ref<CSSValue> valueForNinePieceImageRepeat(const NinePieceImage& image)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto horizontalRepeat = cssValuePool.createIdentifierValue(valueForRepeatRule(image.horizontalRule()));
    RefPtr<CSSPrimitiveValue> verticalRepeat;
    if (image.horizontalRule() == image.verticalRule())
        verticalRepeat = horizontalRepeat.copyRef();
    else
        verticalRepeat = cssValuePool.createIdentifierValue(valueForRepeatRule(image.verticalRule()));
    return cssValuePool.createValue(Pair::create(WTFMove(horizontalRepeat), WTFMove(verticalRepeat)));
}

static Ref<CSSValue> valueForNinePieceImage(const NinePieceImage& image)
{
    if (!image.hasImage())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    // Image first.
    RefPtr<CSSValue> imageValue;
    if (image.image())
        imageValue = image.image()->cssValue();

    // Create the image slice.
    RefPtr<CSSBorderImageSliceValue> imageSlices = valueForNinePieceImageSlice(image);

    // Create the border area slices.
    RefPtr<CSSValue> borderSlices = valueForNinePieceImageQuad(image.borderSlices());

    // Create the border outset.
    RefPtr<CSSValue> outset = valueForNinePieceImageQuad(image.outset());

    // Create the repeat rules.
    RefPtr<CSSValue> repeat = valueForNinePieceImageRepeat(image);

    return createBorderImageValue(WTFMove(imageValue), WTFMove(imageSlices), WTFMove(borderSlices), WTFMove(outset), WTFMove(repeat));
}

inline static Ref<CSSPrimitiveValue> zoomAdjustedPixelValue(double value, const RenderStyle& style)
{
    return CSSValuePool::singleton().createValue(adjustFloatForAbsoluteZoom(value, style), CSSPrimitiveValue::CSS_PX);
}

inline static Ref<CSSPrimitiveValue> zoomAdjustedNumberValue(double value, const RenderStyle& style)
{
    return CSSValuePool::singleton().createValue(value / style.effectiveZoom(), CSSPrimitiveValue::CSS_NUMBER);
}

static Ref<CSSValue> zoomAdjustedPixelValueForLength(const Length& length, const RenderStyle& style)
{
    if (length.isFixed())
        return zoomAdjustedPixelValue(length.value(), style);
    return CSSValuePool::singleton().createValue(length, style);
}

static Ref<CSSValue> valueForReflection(const StyleReflection* reflection, const RenderStyle& style)
{
    if (!reflection)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    RefPtr<CSSPrimitiveValue> offset;
    if (reflection->offset().isPercentOrCalculated())
        offset = CSSValuePool::singleton().createValue(reflection->offset().percent(), CSSPrimitiveValue::CSS_PERCENTAGE);
    else
        offset = zoomAdjustedPixelValue(reflection->offset().value(), style);

    RefPtr<CSSPrimitiveValue> direction;
    switch (reflection->direction()) {
    case ReflectionBelow:
        direction = CSSValuePool::singleton().createIdentifierValue(CSSValueBelow);
        break;
    case ReflectionAbove:
        direction = CSSValuePool::singleton().createIdentifierValue(CSSValueAbove);
        break;
    case ReflectionLeft:
        direction = CSSValuePool::singleton().createIdentifierValue(CSSValueLeft);
        break;
    case ReflectionRight:
        direction = CSSValuePool::singleton().createIdentifierValue(CSSValueRight);
        break;
    }

    return CSSReflectValue::create(direction.releaseNonNull(), offset.releaseNonNull(), valueForNinePieceImage(reflection->mask()));
}

static Ref<CSSValueList> createPositionListForLayer(CSSPropertyID propertyID, const FillLayer& layer, const RenderStyle& style)
{
    auto list = CSSValueList::createSpaceSeparated();
    if (layer.isBackgroundXOriginSet()) {
        ASSERT_UNUSED(propertyID, propertyID == CSSPropertyBackgroundPosition || propertyID == CSSPropertyWebkitMaskPosition);
        list->append(CSSValuePool::singleton().createValue(layer.backgroundXOrigin()));
    }
    list->append(zoomAdjustedPixelValueForLength(layer.xPosition(), style));
    if (layer.isBackgroundYOriginSet()) {
        ASSERT(propertyID == CSSPropertyBackgroundPosition || propertyID == CSSPropertyWebkitMaskPosition);
        list->append(CSSValuePool::singleton().createValue(layer.backgroundYOrigin()));
    }
    list->append(zoomAdjustedPixelValueForLength(layer.yPosition(), style));
    return list;
}

static Length getOffsetComputedLength(const RenderStyle& style, CSSPropertyID propertyID)
{
    // If specified as a length, the corresponding absolute length; if specified as
    // a percentage, the specified value; otherwise, 'auto'. Hence, we can just
    // return the value in the style.
    //
    // See http://www.w3.org/TR/CSS21/cascade.html#computed-value
    switch (propertyID) {
    case CSSPropertyLeft:
        return style.left();
    case CSSPropertyRight:
        return style.right();
    case CSSPropertyTop:
        return style.top();
    case CSSPropertyBottom:
        return style.bottom();
    default:
        ASSERT_NOT_REACHED();
    }

    return { };
}

static LayoutUnit getOffsetUsedStyleRelative(RenderBox& box, CSSPropertyID propertyID)
{
    // For relatively positioned boxes, the offset is with respect to the top edges
    // of the box itself. This ties together top/bottom and left/right to be
    // opposites of each other.
    //
    // See http://www.w3.org/TR/CSS2/visuren.html#relative-positioning
    //
    // Specifically;
    //   Since boxes are not split or stretched as a result of 'left' or
    //   'right', the used values are always: left = -right.
    // and
    //   Since boxes are not split or stretched as a result of 'top' or
    //   'bottom', the used values are always: top = -bottom.
    switch (propertyID) {
    case CSSPropertyTop:
        return box.relativePositionOffset().height();
    case CSSPropertyBottom:
        return -(box.relativePositionOffset().height());
    case CSSPropertyLeft:
        return box.relativePositionOffset().width();
    case CSSPropertyRight:
        return -(box.relativePositionOffset().width());
    default:
        ASSERT_NOT_REACHED();
    }

    return 0;
}

static LayoutUnit getOffsetUsedStyleOutOfFlowPositioned(RenderBlock& container, RenderBox& box, CSSPropertyID propertyID)
{
    // For out-of-flow positioned boxes, the offset is how far an box's margin
    // edge is offset below the edge of the box's containing block.
    // See http://www.w3.org/TR/CSS2/visuren.html#position-props

    // Margins are included in offsetTop/offsetLeft so we need to remove them here.
    switch (propertyID) {
    case CSSPropertyTop:
        return box.offsetTop() - box.marginTop();
    case CSSPropertyBottom:
        return container.clientHeight() - (box.offsetTop() + box.offsetHeight()) - box.marginBottom();
    case CSSPropertyLeft:
        return box.offsetLeft() - box.marginLeft();
    case CSSPropertyRight:
        return container.clientWidth() - (box.offsetLeft() + box.offsetWidth()) - box.marginRight();
    default:
        ASSERT_NOT_REACHED();
    }

    return 0;
}

static RefPtr<CSSValue> positionOffsetValue(const RenderStyle& style, CSSPropertyID propertyID, RenderObject* renderer)
{
    // If the element is not displayed; return the "computed value".
    if (!renderer || !renderer->isBox())
        return zoomAdjustedPixelValueForLength(getOffsetComputedLength(style, propertyID), style);

    // We should return the "used value".
    auto& box = downcast<RenderBox>(*renderer);
    auto* containingBlock = box.containingBlock();
    if (box.isRelativelyPositioned() || !containingBlock)
        return zoomAdjustedPixelValue(getOffsetUsedStyleRelative(box, propertyID), style);
    if (renderer->isOutOfFlowPositioned())
        return zoomAdjustedPixelValue(getOffsetUsedStyleOutOfFlowPositioned(*containingBlock, box, propertyID), style);
    // In-flow element.
    auto offset = getOffsetComputedLength(style, propertyID);
    if (offset.isAuto())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAuto);
    return zoomAdjustedPixelValueForLength(offset, style);
}

RefPtr<CSSPrimitiveValue> ComputedStyleExtractor::currentColorOrValidColor(const RenderStyle* style, const Color& color) const
{
    // This function does NOT look at visited information, so that computed style doesn't expose that.
    if (!color.isValid())
        return CSSValuePool::singleton().createColorValue(style->color());
    return CSSValuePool::singleton().createColorValue(color);
}

static Ref<CSSPrimitiveValue> percentageOrZoomAdjustedValue(Length length, const RenderStyle& style)
{
    if (length.isPercent())
        return CSSValuePool::singleton().createValue(length.percent(), CSSPrimitiveValue::CSS_PERCENTAGE);

    return zoomAdjustedPixelValue(valueForLength(length, 0), style);
}

static Ref<CSSPrimitiveValue> autoOrZoomAdjustedValue(Length length, const RenderStyle& style)
{
    if (length.isAuto())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAuto);

    return zoomAdjustedPixelValue(valueForLength(length, 0), style);
}

static Ref<CSSValueList> borderRadiusCornerValues(const LengthSize& radius, const RenderStyle& style)
{
    auto list = CSSValueList::createSpaceSeparated();
    list->append(percentageOrZoomAdjustedValue(radius.width, style));
    list->append(percentageOrZoomAdjustedValue(radius.height, style));
    return list;
}

static Ref<CSSValue> borderRadiusCornerValue(const LengthSize& radius, const RenderStyle& style)
{
    if (radius.width == radius.height)
        return percentageOrZoomAdjustedValue(radius.width, style);
    return borderRadiusCornerValues(radius, style);
}

static Ref<CSSValueList> borderRadiusShorthandValue(const RenderStyle& style)
{
    auto list = CSSValueList::createSlashSeparated();
    bool showHorizontalBottomLeft = style.borderTopRightRadius().width != style.borderBottomLeftRadius().width;
    bool showHorizontalBottomRight = showHorizontalBottomLeft || (style.borderBottomRightRadius().width != style.borderTopLeftRadius().width);
    bool showHorizontalTopRight = showHorizontalBottomRight || (style.borderTopRightRadius().width != style.borderTopLeftRadius().width);

    bool showVerticalBottomLeft = style.borderTopRightRadius().height != style.borderBottomLeftRadius().height;
    bool showVerticalBottomRight = showVerticalBottomLeft || (style.borderBottomRightRadius().height != style.borderTopLeftRadius().height);
    bool showVerticalTopRight = showVerticalBottomRight || (style.borderTopRightRadius().height != style.borderTopLeftRadius().height);

    auto topLeftRadius = borderRadiusCornerValues(style.borderTopLeftRadius(), style);
    auto topRightRadius = borderRadiusCornerValues(style.borderTopRightRadius(), style);
    auto bottomRightRadius = borderRadiusCornerValues(style.borderBottomRightRadius(), style);
    auto bottomLeftRadius = borderRadiusCornerValues(style.borderBottomLeftRadius(), style);

    auto horizontalRadii = CSSValueList::createSpaceSeparated();
    horizontalRadii->append(*topLeftRadius->item(0));
    if (showHorizontalTopRight)
        horizontalRadii->append(*topRightRadius->item(0));
    if (showHorizontalBottomRight)
        horizontalRadii->append(*bottomRightRadius->item(0));
    if (showHorizontalBottomLeft)
        horizontalRadii->append(*bottomLeftRadius->item(0));

    list->append(WTFMove(horizontalRadii));

    auto verticalRadiiList = CSSValueList::createSpaceSeparated();
    verticalRadiiList->append(*topLeftRadius->item(1));
    if (showVerticalTopRight)
        verticalRadiiList->append(*topRightRadius->item(1));
    if (showVerticalBottomRight)
        verticalRadiiList->append(*bottomRightRadius->item(1));
    if (showVerticalBottomLeft)
        verticalRadiiList->append(*bottomLeftRadius->item(1));

    if (!verticalRadiiList->equals(downcast<CSSValueList>(*list->item(0))))
        list->append(WTFMove(verticalRadiiList));

    return list;
}

static LayoutRect sizingBox(RenderObject& renderer)
{
    if (!is<RenderBox>(renderer))
        return LayoutRect();

    auto& box = downcast<RenderBox>(renderer);
    return box.style().boxSizing() == BoxSizing::BorderBox ? box.borderBoxRect() : box.computedCSSContentBoxRect();
}

static Ref<CSSFunctionValue> matrixTransformValue(const TransformationMatrix& transform, const RenderStyle& style)
{
    RefPtr<CSSFunctionValue> transformValue;
    auto& cssValuePool = CSSValuePool::singleton();
    if (transform.isAffine()) {
        transformValue = CSSFunctionValue::create(CSSValueMatrix);

        transformValue->append(cssValuePool.createValue(transform.a(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.b(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.c(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.d(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(zoomAdjustedNumberValue(transform.e(), style));
        transformValue->append(zoomAdjustedNumberValue(transform.f(), style));
    } else {
        transformValue = CSSFunctionValue::create(CSSValueMatrix3d);

        transformValue->append(cssValuePool.createValue(transform.m11(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m12(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m13(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m14(), CSSPrimitiveValue::CSS_NUMBER));

        transformValue->append(cssValuePool.createValue(transform.m21(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m22(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m23(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m24(), CSSPrimitiveValue::CSS_NUMBER));

        transformValue->append(cssValuePool.createValue(transform.m31(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m32(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m33(), CSSPrimitiveValue::CSS_NUMBER));
        transformValue->append(cssValuePool.createValue(transform.m34(), CSSPrimitiveValue::CSS_NUMBER));

        transformValue->append(zoomAdjustedNumberValue(transform.m41(), style));
        transformValue->append(zoomAdjustedNumberValue(transform.m42(), style));
        transformValue->append(zoomAdjustedNumberValue(transform.m43(), style));
        transformValue->append(cssValuePool.createValue(transform.m44(), CSSPrimitiveValue::CSS_NUMBER));
    }

    return transformValue.releaseNonNull();
}

static Ref<CSSValue> computedTransform(RenderObject* renderer, const RenderStyle& style)
{
    // Inline renderers do not support transforms.
    if (!renderer || is<RenderInline>(*renderer) || !style.hasTransform())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    FloatRect pixelSnappedRect;
    if (is<RenderBox>(*renderer))
        pixelSnappedRect = snapRectToDevicePixels(downcast<RenderBox>(*renderer).borderBoxRect(), renderer->document().deviceScaleFactor());

    TransformationMatrix transform;
    style.applyTransform(transform, pixelSnappedRect, RenderStyle::ExcludeTransformOrigin);
    // Note that this does not flatten to an affine transform if ENABLE(3D_TRANSFORMS) is off, by design.

    // FIXME: Need to print out individual functions (https://bugs.webkit.org/show_bug.cgi?id=23924)
    auto list = CSSValueList::createSpaceSeparated();
    list->append(matrixTransformValue(transform, style));
    return WTFMove(list);
}

static inline Ref<CSSPrimitiveValue> adjustLengthForZoom(double length, const RenderStyle& style, AdjustPixelValuesForComputedStyle adjust)
{
    return adjust == AdjustPixelValues ? zoomAdjustedPixelValue(length, style) : CSSValuePool::singleton().createValue(length, CSSPrimitiveValue::CSS_PX);
}

static inline Ref<CSSPrimitiveValue> adjustLengthForZoom(const Length& length, const RenderStyle& style, AdjustPixelValuesForComputedStyle adjust)
{
    return adjust == AdjustPixelValues ? zoomAdjustedPixelValue(length.value(), style) : CSSValuePool::singleton().createValue(length);
}

Ref<CSSValue> ComputedStyleExtractor::valueForShadow(const ShadowData* shadow, CSSPropertyID propertyID, const RenderStyle& style, AdjustPixelValuesForComputedStyle adjust)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (!shadow)
        return cssValuePool.createIdentifierValue(CSSValueNone);

    auto list = CSSValueList::createCommaSeparated();
    for (const ShadowData* currShadowData = shadow; currShadowData; currShadowData = currShadowData->next()) {
        auto x = adjustLengthForZoom(currShadowData->x(), style, adjust);
        auto y = adjustLengthForZoom(currShadowData->y(), style, adjust);
        auto blur = adjustLengthForZoom(currShadowData->radius(), style, adjust);
        auto spread = propertyID == CSSPropertyTextShadow ? RefPtr<CSSPrimitiveValue>() : adjustLengthForZoom(currShadowData->spread(), style, adjust);
        auto style = propertyID == CSSPropertyTextShadow || currShadowData->style() == Normal ? RefPtr<CSSPrimitiveValue>() : cssValuePool.createIdentifierValue(CSSValueInset);
        auto color = cssValuePool.createColorValue(currShadowData->color());
        list->prepend(CSSShadowValue::create(WTFMove(x), WTFMove(y), WTFMove(blur), WTFMove(spread), WTFMove(style), WTFMove(color)));
    }
    return WTFMove(list);
}

Ref<CSSValue> ComputedStyleExtractor::valueForFilter(const RenderStyle& style, const FilterOperations& filterOperations, AdjustPixelValuesForComputedStyle adjust)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (filterOperations.operations().isEmpty())
        return cssValuePool.createIdentifierValue(CSSValueNone);

    auto list = CSSValueList::createSpaceSeparated();

    Vector<RefPtr<FilterOperation>>::const_iterator end = filterOperations.operations().end();
    for (Vector<RefPtr<FilterOperation>>::const_iterator it = filterOperations.operations().begin(); it != end; ++it) {
        FilterOperation& filterOperation = **it;

        if (filterOperation.type() == FilterOperation::REFERENCE) {
            ReferenceFilterOperation& referenceOperation = downcast<ReferenceFilterOperation>(filterOperation);
            list->append(cssValuePool.createValue(referenceOperation.url(), CSSPrimitiveValue::CSS_URI));
        } else {
            RefPtr<CSSFunctionValue> filterValue;
            switch (filterOperation.type()) {
            case FilterOperation::GRAYSCALE: {
                filterValue = CSSFunctionValue::create(CSSValueGrayscale);
                filterValue->append(cssValuePool.createValue(downcast<BasicColorMatrixFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::SEPIA: {
                filterValue = CSSFunctionValue::create(CSSValueSepia);
                filterValue->append(cssValuePool.createValue(downcast<BasicColorMatrixFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::SATURATE: {
                filterValue = CSSFunctionValue::create(CSSValueSaturate);
                filterValue->append(cssValuePool.createValue(downcast<BasicColorMatrixFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::HUE_ROTATE: {
                filterValue = CSSFunctionValue::create(CSSValueHueRotate);
                filterValue->append(cssValuePool.createValue(downcast<BasicColorMatrixFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_DEG));
                break;
            }
            case FilterOperation::INVERT: {
                filterValue = CSSFunctionValue::create(CSSValueInvert);
                filterValue->append(cssValuePool.createValue(downcast<BasicComponentTransferFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::APPLE_INVERT_LIGHTNESS: {
                filterValue = CSSFunctionValue::create(CSSValueAppleInvertLightness);
                break;
            }
            case FilterOperation::OPACITY: {
                filterValue = CSSFunctionValue::create(CSSValueOpacity);
                filterValue->append(cssValuePool.createValue(downcast<BasicComponentTransferFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::BRIGHTNESS: {
                filterValue = CSSFunctionValue::create(CSSValueBrightness);
                filterValue->append(cssValuePool.createValue(downcast<BasicComponentTransferFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::CONTRAST: {
                filterValue = CSSFunctionValue::create(CSSValueContrast);
                filterValue->append(cssValuePool.createValue(downcast<BasicComponentTransferFilterOperation>(filterOperation).amount(), CSSPrimitiveValue::CSS_NUMBER));
                break;
            }
            case FilterOperation::BLUR: {
                filterValue = CSSFunctionValue::create(CSSValueBlur);
                filterValue->append(adjustLengthForZoom(downcast<BlurFilterOperation>(filterOperation).stdDeviation(), style, adjust));
                break;
            }
            case FilterOperation::DROP_SHADOW: {
                DropShadowFilterOperation& dropShadowOperation = downcast<DropShadowFilterOperation>(filterOperation);
                filterValue = CSSFunctionValue::create(CSSValueDropShadow);
                // We want our computed style to look like that of a text shadow (has neither spread nor inset style).
                ShadowData shadowData = ShadowData(dropShadowOperation.location(), dropShadowOperation.stdDeviation(), 0, Normal, false, dropShadowOperation.color());
                filterValue->append(valueForShadow(&shadowData, CSSPropertyTextShadow, style, adjust));
                break;
            }
            default:
                ASSERT_NOT_REACHED();
                filterValue = CSSFunctionValue::create(CSSValueInvalid);
                break;
            }
            list->append(filterValue.releaseNonNull());
        }
    }
    return WTFMove(list);
}

static Ref<CSSValue> specifiedValueForGridTrackBreadth(const GridLength& trackBreadth, const RenderStyle& style)
{
    if (!trackBreadth.isLength())
        return CSSValuePool::singleton().createValue(trackBreadth.flex(), CSSPrimitiveValue::CSS_FR);

    const Length& trackBreadthLength = trackBreadth.length();
    if (trackBreadthLength.isAuto())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAuto);
    return zoomAdjustedPixelValueForLength(trackBreadthLength, style);
}

static Ref<CSSValue> specifiedValueForGridTrackSize(const GridTrackSize& trackSize, const RenderStyle& style)
{
    switch (trackSize.type()) {
    case LengthTrackSizing:
        return specifiedValueForGridTrackBreadth(trackSize.minTrackBreadth(), style);
    case FitContentTrackSizing: {
        auto fitContentTrackSize = CSSFunctionValue::create(CSSValueFitContent);
        fitContentTrackSize->append(zoomAdjustedPixelValueForLength(trackSize.fitContentTrackBreadth().length(), style));
        return WTFMove(fitContentTrackSize);
    }
    default:
        ASSERT(trackSize.type() == MinMaxTrackSizing);
        if (trackSize.minTrackBreadth().isAuto() && trackSize.maxTrackBreadth().isFlex())
            return CSSValuePool::singleton().createValue(trackSize.maxTrackBreadth().flex(), CSSPrimitiveValue::CSS_FR);

        auto minMaxTrackBreadths = CSSFunctionValue::create(CSSValueMinmax);
        minMaxTrackBreadths->append(specifiedValueForGridTrackBreadth(trackSize.minTrackBreadth(), style));
        minMaxTrackBreadths->append(specifiedValueForGridTrackBreadth(trackSize.maxTrackBreadth(), style));
        return WTFMove(minMaxTrackBreadths);
    }
}

class OrderedNamedLinesCollector {
    WTF_MAKE_NONCOPYABLE(OrderedNamedLinesCollector);
public:
    OrderedNamedLinesCollector(const RenderStyle& style, bool isRowAxis, unsigned autoRepeatTracksCount)
        : m_orderedNamedGridLines(isRowAxis ? style.orderedNamedGridColumnLines() : style.orderedNamedGridRowLines())
        , m_orderedNamedAutoRepeatGridLines(isRowAxis ? style.autoRepeatOrderedNamedGridColumnLines() : style.autoRepeatOrderedNamedGridRowLines())
        , m_insertionPoint(isRowAxis ? style.gridAutoRepeatColumnsInsertionPoint() : style.gridAutoRepeatRowsInsertionPoint())
        , m_autoRepeatTotalTracks(autoRepeatTracksCount)
        , m_autoRepeatTrackListLength(isRowAxis ? style.gridAutoRepeatColumns().size() : style.gridAutoRepeatRows().size())
    {
    }

    bool isEmpty() const { return m_orderedNamedGridLines.isEmpty() && m_orderedNamedAutoRepeatGridLines.isEmpty(); }
    void collectLineNamesForIndex(CSSGridLineNamesValue&, unsigned index) const;

private:

    enum NamedLinesType { NamedLines, AutoRepeatNamedLines };
    void appendLines(CSSGridLineNamesValue&, unsigned index, NamedLinesType) const;

    const OrderedNamedGridLinesMap& m_orderedNamedGridLines;
    const OrderedNamedGridLinesMap& m_orderedNamedAutoRepeatGridLines;
    unsigned m_insertionPoint;
    unsigned m_autoRepeatTotalTracks;
    unsigned m_autoRepeatTrackListLength;
};

void OrderedNamedLinesCollector::appendLines(CSSGridLineNamesValue& lineNamesValue, unsigned index, NamedLinesType type) const
{
    auto iter = type == NamedLines ? m_orderedNamedGridLines.find(index) : m_orderedNamedAutoRepeatGridLines.find(index);
    auto endIter = type == NamedLines ? m_orderedNamedGridLines.end() : m_orderedNamedAutoRepeatGridLines.end();
    if (iter == endIter)
        return;

    auto& cssValuePool = CSSValuePool::singleton();
    for (auto lineName : iter->value)
        lineNamesValue.append(cssValuePool.createValue(lineName, CSSPrimitiveValue::CSS_STRING));
}

void OrderedNamedLinesCollector::collectLineNamesForIndex(CSSGridLineNamesValue& lineNamesValue, unsigned i) const
{
    ASSERT(!isEmpty());
    if (m_orderedNamedAutoRepeatGridLines.isEmpty() || i < m_insertionPoint) {
        appendLines(lineNamesValue, i, NamedLines);
        return;
    }

    ASSERT(m_autoRepeatTotalTracks);

    if (i > m_insertionPoint + m_autoRepeatTotalTracks) {
        appendLines(lineNamesValue, i - (m_autoRepeatTotalTracks - 1), NamedLines);
        return;
    }

    if (i == m_insertionPoint) {
        appendLines(lineNamesValue, i, NamedLines);
        appendLines(lineNamesValue, 0, AutoRepeatNamedLines);
        return;
    }

    if (i == m_insertionPoint + m_autoRepeatTotalTracks) {
        appendLines(lineNamesValue, m_autoRepeatTrackListLength, AutoRepeatNamedLines);
        appendLines(lineNamesValue, m_insertionPoint + 1, NamedLines);
        return;
    }

    unsigned autoRepeatIndexInFirstRepetition = (i - m_insertionPoint) % m_autoRepeatTrackListLength;
    if (!autoRepeatIndexInFirstRepetition && i > m_insertionPoint)
        appendLines(lineNamesValue, m_autoRepeatTrackListLength, AutoRepeatNamedLines);
    appendLines(lineNamesValue, autoRepeatIndexInFirstRepetition, AutoRepeatNamedLines);
}

static void addValuesForNamedGridLinesAtIndex(OrderedNamedLinesCollector& collector, unsigned i, CSSValueList& list)
{
    if (collector.isEmpty())
        return;

    auto lineNames = CSSGridLineNamesValue::create();
    collector.collectLineNamesForIndex(lineNames.get(), i);
    if (lineNames->length())
        list.append(WTFMove(lineNames));
}

static Ref<CSSValueList> valueForGridTrackSizeList(GridTrackSizingDirection direction, const RenderStyle& style)
{
    auto& autoTrackSizes = direction == ForColumns ? style.gridAutoColumns() : style.gridAutoRows();

    auto list = CSSValueList::createSpaceSeparated();
    for (auto& trackSize : autoTrackSizes)
        list->append(specifiedValueForGridTrackSize(trackSize, style));
    return list;
}

static Ref<CSSValue> valueForGridTrackList(GridTrackSizingDirection direction, RenderObject* renderer, const RenderStyle& style)
{
    bool isRowAxis = direction == ForColumns;
    bool isRenderGrid = is<RenderGrid>(renderer);
    auto& trackSizes = isRowAxis ? style.gridColumns() : style.gridRows();
    auto& autoRepeatTrackSizes = isRowAxis ? style.gridAutoRepeatColumns() : style.gridAutoRepeatRows();

    // Handle the 'none' case.
    bool trackListIsEmpty = trackSizes.isEmpty() && autoRepeatTrackSizes.isEmpty();
    if (isRenderGrid && trackListIsEmpty) {
        // For grids we should consider every listed track, whether implicitly or explicitly
        // created. Empty grids have a sole grid line per axis.
        auto& grid = downcast<RenderGrid>(*renderer);
        auto& positions = isRowAxis ? grid.columnPositions() : grid.rowPositions();
        trackListIsEmpty = positions.size() == 1;
    }

    if (trackListIsEmpty)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    unsigned autoRepeatTotalTracks = isRenderGrid ? downcast<RenderGrid>(renderer)->autoRepeatCountForDirection(direction) : 0;
    OrderedNamedLinesCollector collector(style, isRowAxis, autoRepeatTotalTracks);
    auto list = CSSValueList::createSpaceSeparated();
    unsigned insertionIndex;
    if (isRenderGrid) {
        auto computedTrackSizes = downcast<RenderGrid>(*renderer).trackSizesForComputedStyle(direction);
        unsigned numTracks = computedTrackSizes.size();

        for (unsigned i = 0; i < numTracks; ++i) {
            addValuesForNamedGridLinesAtIndex(collector, i, list.get());
            list->append(zoomAdjustedPixelValue(computedTrackSizes[i], style));
        }
        addValuesForNamedGridLinesAtIndex(collector, numTracks + 1, list.get());
        insertionIndex = numTracks;
    } else {
        for (unsigned i = 0; i < trackSizes.size(); ++i) {
            addValuesForNamedGridLinesAtIndex(collector, i, list.get());
            list->append(specifiedValueForGridTrackSize(trackSizes[i], style));
        }
        insertionIndex = trackSizes.size();
    }

    // Those are the trailing <ident>* allowed in the syntax.
    addValuesForNamedGridLinesAtIndex(collector, insertionIndex, list.get());
    return WTFMove(list);
}

static Ref<CSSValue> valueForGridPosition(const GridPosition& position)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (position.isAuto())
        return cssValuePool.createIdentifierValue(CSSValueAuto);

    if (position.isNamedGridArea())
        return cssValuePool.createValue(position.namedGridLine(), CSSPrimitiveValue::CSS_STRING);

    auto list = CSSValueList::createSpaceSeparated();
    if (position.isSpan()) {
        list->append(cssValuePool.createIdentifierValue(CSSValueSpan));
        list->append(cssValuePool.createValue(position.spanPosition(), CSSPrimitiveValue::CSS_NUMBER));
    } else
        list->append(cssValuePool.createValue(position.integerPosition(), CSSPrimitiveValue::CSS_NUMBER));

    if (!position.namedGridLine().isNull())
        list->append(cssValuePool.createValue(position.namedGridLine(), CSSPrimitiveValue::CSS_STRING));
    return WTFMove(list);
}

static Ref<CSSValue> createTransitionPropertyValue(const Animation& animation)
{
    switch (animation.animationMode()) {
    case Animation::AnimateNone:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);
    case Animation::AnimateAll:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAll);
    case Animation::AnimateSingleProperty:
        return CSSValuePool::singleton().createValue(getPropertyNameString(animation.property()), CSSPrimitiveValue::CSS_STRING);
    case Animation::AnimateUnknownProperty:
        return CSSValuePool::singleton().createValue(animation.unknownProperty(), CSSPrimitiveValue::CSS_STRING);
    }
    ASSERT_NOT_REACHED();
    return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);
}

static Ref<CSSValueList> transitionPropertyValue(const AnimationList* animationList)
{
    auto list = CSSValueList::createCommaSeparated();
    if (animationList) {
        for (size_t i = 0; i < animationList->size(); ++i)
            list->append(createTransitionPropertyValue(animationList->animation(i)));
    } else
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueAll));
    return list;
}

#if ENABLE(CSS_SCROLL_SNAP)

static Ref<CSSValueList> valueForScrollSnapType(const ScrollSnapType& type)
{
    auto value = CSSValueList::createSpaceSeparated();
    if (type.strictness == ScrollSnapStrictness::None)
        value->append(CSSValuePool::singleton().createValue(CSSValueNone));
    else {
        value->append(CSSPrimitiveValue::create(type.axis));
        value->append(CSSPrimitiveValue::create(type.strictness));
    }
    return value;
}

static Ref<CSSValueList> valueForScrollSnapAlignment(const ScrollSnapAlign& alignment)
{
    auto value = CSSValueList::createSpaceSeparated();
    value->append(CSSPrimitiveValue::create(alignment.x));
    value->append(CSSPrimitiveValue::create(alignment.y));
    return value;
}

#endif

static Ref<CSSValue> willChangePropertyValue(const WillChangeData* willChangeData)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (!willChangeData || !willChangeData->numFeatures())
        return cssValuePool.createIdentifierValue(CSSValueAuto);

    auto list = CSSValueList::createCommaSeparated();
    for (size_t i = 0; i < willChangeData->numFeatures(); ++i) {
        WillChangeData::FeaturePropertyPair feature = willChangeData->featureAt(i);
        switch (feature.first) {
        case WillChangeData::ScrollPosition:
            list->append(cssValuePool.createIdentifierValue(CSSValueScrollPosition));
            break;
        case WillChangeData::Contents:
            list->append(cssValuePool.createIdentifierValue(CSSValueContents));
            break;
        case WillChangeData::Property:
            list->append(cssValuePool.createIdentifierValue(feature.second));
            break;
        case WillChangeData::Invalid:
            ASSERT_NOT_REACHED();
            break;
        }
    }

    return WTFMove(list);
}

static inline void appendLigaturesValue(CSSValueList& list, FontVariantLigatures value, CSSValueID yesValue, CSSValueID noValue)
{
    switch (value) {
    case FontVariantLigatures::Normal:
        return;
    case FontVariantLigatures::No:
        list.append(CSSValuePool::singleton().createIdentifierValue(noValue));
        return;
    case FontVariantLigatures::Yes:
        list.append(CSSValuePool::singleton().createIdentifierValue(yesValue));
        return;
    }
    ASSERT_NOT_REACHED();
}

static Ref<CSSValue> fontVariantLigaturesPropertyValue(FontVariantLigatures common, FontVariantLigatures discretionary, FontVariantLigatures historical, FontVariantLigatures contextualAlternates)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (common == FontVariantLigatures::No && discretionary == FontVariantLigatures::No && historical == FontVariantLigatures::No && contextualAlternates == FontVariantLigatures::No)
        return cssValuePool.createIdentifierValue(CSSValueNone);
    if (common == FontVariantLigatures::Normal && discretionary == FontVariantLigatures::Normal && historical == FontVariantLigatures::Normal && contextualAlternates == FontVariantLigatures::Normal)
        return cssValuePool.createIdentifierValue(CSSValueNormal);

    auto valueList = CSSValueList::createSpaceSeparated();
    appendLigaturesValue(valueList, common, CSSValueCommonLigatures, CSSValueNoCommonLigatures);
    appendLigaturesValue(valueList, discretionary, CSSValueDiscretionaryLigatures, CSSValueNoDiscretionaryLigatures);
    appendLigaturesValue(valueList, historical, CSSValueHistoricalLigatures, CSSValueNoHistoricalLigatures);
    appendLigaturesValue(valueList, contextualAlternates, CSSValueContextual, CSSValueNoContextual);
    return WTFMove(valueList);
}

static Ref<CSSValue> fontVariantPositionPropertyValue(FontVariantPosition position)
{
    auto& cssValuePool = CSSValuePool::singleton();
    CSSValueID valueID = CSSValueNormal;
    switch (position) {
    case FontVariantPosition::Normal:
        break;
    case FontVariantPosition::Subscript:
        valueID = CSSValueSub;
        break;
    case FontVariantPosition::Superscript:
        valueID = CSSValueSuper;
        break;
    }
    return cssValuePool.createIdentifierValue(valueID);
}

static Ref<CSSValue> fontVariantCapsPropertyValue(FontVariantCaps caps)
{
    auto& cssValuePool = CSSValuePool::singleton();
    CSSValueID valueID = CSSValueNormal;
    switch (caps) {
    case FontVariantCaps::Normal:
        break;
    case FontVariantCaps::Small:
        valueID = CSSValueSmallCaps;
        break;
    case FontVariantCaps::AllSmall:
        valueID = CSSValueAllSmallCaps;
        break;
    case FontVariantCaps::Petite:
        valueID = CSSValuePetiteCaps;
        break;
    case FontVariantCaps::AllPetite:
        valueID = CSSValueAllPetiteCaps;
        break;
    case FontVariantCaps::Unicase:
        valueID = CSSValueUnicase;
        break;
    case FontVariantCaps::Titling:
        valueID = CSSValueTitlingCaps;
        break;
    }
    return cssValuePool.createIdentifierValue(valueID);
}

static Ref<CSSValue> fontVariantNumericPropertyValue(FontVariantNumericFigure figure, FontVariantNumericSpacing spacing, FontVariantNumericFraction fraction, FontVariantNumericOrdinal ordinal, FontVariantNumericSlashedZero slashedZero)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (figure == FontVariantNumericFigure::Normal && spacing == FontVariantNumericSpacing::Normal && fraction == FontVariantNumericFraction::Normal && ordinal == FontVariantNumericOrdinal::Normal && slashedZero == FontVariantNumericSlashedZero::Normal)
        return cssValuePool.createIdentifierValue(CSSValueNormal);

    auto valueList = CSSValueList::createSpaceSeparated();
    switch (figure) {
    case FontVariantNumericFigure::Normal:
        break;
    case FontVariantNumericFigure::LiningNumbers:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueLiningNums));
        break;
    case FontVariantNumericFigure::OldStyleNumbers:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueOldstyleNums));
        break;
    }

    switch (spacing) {
    case FontVariantNumericSpacing::Normal:
        break;
    case FontVariantNumericSpacing::ProportionalNumbers:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueProportionalNums));
        break;
    case FontVariantNumericSpacing::TabularNumbers:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueTabularNums));
        break;
    }

    switch (fraction) {
    case FontVariantNumericFraction::Normal:
        break;
    case FontVariantNumericFraction::DiagonalFractions:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueDiagonalFractions));
        break;
    case FontVariantNumericFraction::StackedFractions:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueStackedFractions));
        break;
    }

    if (ordinal == FontVariantNumericOrdinal::Yes)
        valueList->append(cssValuePool.createIdentifierValue(CSSValueOrdinal));
    if (slashedZero == FontVariantNumericSlashedZero::Yes)
        valueList->append(cssValuePool.createIdentifierValue(CSSValueSlashedZero));

    return WTFMove(valueList);
}

static Ref<CSSValue> fontVariantAlternatesPropertyValue(FontVariantAlternates alternates)
{
    auto& cssValuePool = CSSValuePool::singleton();
    CSSValueID valueID = CSSValueNormal;
    switch (alternates) {
    case FontVariantAlternates::Normal:
        break;
    case FontVariantAlternates::HistoricalForms:
        valueID = CSSValueHistoricalForms;
        break;
    }
    return cssValuePool.createIdentifierValue(valueID);
}

static Ref<CSSValue> fontVariantEastAsianPropertyValue(FontVariantEastAsianVariant variant, FontVariantEastAsianWidth width, FontVariantEastAsianRuby ruby)
{
    auto& cssValuePool = CSSValuePool::singleton();
    if (variant == FontVariantEastAsianVariant::Normal && width == FontVariantEastAsianWidth::Normal && ruby == FontVariantEastAsianRuby::Normal)
        return cssValuePool.createIdentifierValue(CSSValueNormal);

    auto valueList = CSSValueList::createSpaceSeparated();
    switch (variant) {
    case FontVariantEastAsianVariant::Normal:
        break;
    case FontVariantEastAsianVariant::Jis78:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueJis78));
        break;
    case FontVariantEastAsianVariant::Jis83:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueJis83));
        break;
    case FontVariantEastAsianVariant::Jis90:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueJis90));
        break;
    case FontVariantEastAsianVariant::Jis04:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueJis04));
        break;
    case FontVariantEastAsianVariant::Simplified:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueSimplified));
        break;
    case FontVariantEastAsianVariant::Traditional:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueTraditional));
        break;
    }

    switch (width) {
    case FontVariantEastAsianWidth::Normal:
        break;
    case FontVariantEastAsianWidth::Full:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueFullWidth));
        break;
    case FontVariantEastAsianWidth::Proportional:
        valueList->append(cssValuePool.createIdentifierValue(CSSValueProportionalWidth));
        break;
    }

    if (ruby == FontVariantEastAsianRuby::Yes)
        valueList->append(cssValuePool.createIdentifierValue(CSSValueRuby));

    return WTFMove(valueList);
}

static Ref<CSSValueList> delayValue(const AnimationList* animationList)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createCommaSeparated();
    if (animationList) {
        for (size_t i = 0; i < animationList->size(); ++i)
            list->append(cssValuePool.createValue(animationList->animation(i).delay(), CSSPrimitiveValue::CSS_S));
    } else {
        // Note that initialAnimationDelay() is used for both transitions and animations
        list->append(cssValuePool.createValue(Animation::initialDelay(), CSSPrimitiveValue::CSS_S));
    }
    return list;
}

static Ref<CSSValueList> durationValue(const AnimationList* animationList)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createCommaSeparated();
    if (animationList) {
        for (size_t i = 0; i < animationList->size(); ++i)
            list->append(cssValuePool.createValue(animationList->animation(i).duration(), CSSPrimitiveValue::CSS_S));
    } else {
        // Note that initialAnimationDuration() is used for both transitions and animations
        list->append(cssValuePool.createValue(Animation::initialDuration(), CSSPrimitiveValue::CSS_S));
    }
    return list;
}

static Ref<CSSValue> createTimingFunctionValue(const TimingFunction& timingFunction)
{
    switch (timingFunction.type()) {
    case TimingFunction::CubicBezierFunction: {
        auto& function = downcast<CubicBezierTimingFunction>(timingFunction);
        if (function.timingFunctionPreset() != CubicBezierTimingFunction::Custom) {
            CSSValueID valueId = CSSValueInvalid;
            switch (function.timingFunctionPreset()) {
            case CubicBezierTimingFunction::Ease:
                valueId = CSSValueEase;
                break;
            case CubicBezierTimingFunction::EaseIn:
                valueId = CSSValueEaseIn;
                break;
            case CubicBezierTimingFunction::EaseOut:
                valueId = CSSValueEaseOut;
                break;
            default:
                ASSERT(function.timingFunctionPreset() == CubicBezierTimingFunction::EaseInOut);
                valueId = CSSValueEaseInOut;
                break;
            }
            return CSSValuePool::singleton().createIdentifierValue(valueId);
        }
        return CSSCubicBezierTimingFunctionValue::create(function.x1(), function.y1(), function.x2(), function.y2());
    }
    case TimingFunction::StepsFunction: {
        auto& function = downcast<StepsTimingFunction>(timingFunction);
        return CSSStepsTimingFunctionValue::create(function.numberOfSteps(), function.stepAtStart());
    }
    case TimingFunction::FramesFunction: {
        auto& function = downcast<FramesTimingFunction>(timingFunction);
        return CSSFramesTimingFunctionValue::create(function.numberOfFrames());
    }
    case TimingFunction::SpringFunction: {
        auto& function = downcast<SpringTimingFunction>(timingFunction);
        return CSSSpringTimingFunctionValue::create(function.mass(), function.stiffness(), function.damping(), function.initialVelocity());
    }
    default:
        ASSERT(timingFunction.type() == TimingFunction::LinearFunction);
        return CSSValuePool::singleton().createIdentifierValue(CSSValueLinear);
    }
}

static Ref<CSSValueList> timingFunctionValue(const AnimationList* animationList)
{
    auto list = CSSValueList::createCommaSeparated();
    if (animationList) {
        for (size_t i = 0; i < animationList->size(); ++i)
            list->append(createTimingFunctionValue(*animationList->animation(i).timingFunction()));
    } else
        // Note that initialAnimationTimingFunction() is used for both transitions and animations
        list->append(createTimingFunctionValue(Animation::initialTimingFunction()));
    return list;
}

#if ENABLE(CSS_ANIMATIONS_LEVEL_2)

static Ref<CSSValue> createAnimationTriggerValue(const AnimationTrigger& trigger, const RenderStyle& style)
{
    switch (trigger.type()) {
    case AnimationTrigger::AnimationTriggerType::ScrollAnimationTriggerType: {
        auto& scrollAnimationTrigger = downcast<ScrollAnimationTrigger>(trigger);
        if (scrollAnimationTrigger.endValue().isAuto())
            return CSSAnimationTriggerScrollValue::create(zoomAdjustedPixelValueForLength(scrollAnimationTrigger.startValue(), style));
        return CSSAnimationTriggerScrollValue::create(zoomAdjustedPixelValueForLength(scrollAnimationTrigger.startValue(), style),
                                                      zoomAdjustedPixelValueForLength(scrollAnimationTrigger.endValue(), style));
    }
    default:
        ASSERT(trigger.type() == AnimationTrigger::AnimationTriggerType::AutoAnimationTriggerType);
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAuto);
    }
}

static Ref<CSSValueList> animationTriggerValue(const AnimationList* animationList, const RenderStyle& style)
{
    auto list = CSSValueList::createCommaSeparated();
    if (animationList) {
        for (size_t i = 0; i < animationList->size(); ++i)
            list->append(createAnimationTriggerValue(*animationList->animation(i).trigger(), style));
    } else
        list->append(createAnimationTriggerValue(Animation::initialTrigger().get(), style));
    return list;
}

#endif

static Ref<CSSValue> createLineBoxContainValue(unsigned lineBoxContain)
{
    if (!lineBoxContain)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);
    return CSSLineBoxContainValue::create(lineBoxContain);
}

static Element* styleElementForNode(Node* node)
{
    if (!node)
        return nullptr;
    if (is<Element>(*node))
        return downcast<Element>(node);
    return composedTreeAncestors(*node).first();
}

ComputedStyleExtractor::ComputedStyleExtractor(Node* node, bool allowVisitedStyle, PseudoId pseudoElementSpecifier)
    : m_element(styleElementForNode(node))
    , m_pseudoElementSpecifier(pseudoElementSpecifier)
    , m_allowVisitedStyle(allowVisitedStyle)
{
}

ComputedStyleExtractor::ComputedStyleExtractor(Element* element, bool allowVisitedStyle, PseudoId pseudoElementSpecifier)
    : m_element(element)
    , m_pseudoElementSpecifier(pseudoElementSpecifier)
    , m_allowVisitedStyle(allowVisitedStyle)
{
}

CSSComputedStyleDeclaration::CSSComputedStyleDeclaration(Element& element, bool allowVisitedStyle, const String& pseudoElementName)
    : m_element(element)
    , m_allowVisitedStyle(allowVisitedStyle)
    , m_refCount(1)
{
    unsigned nameWithoutColonsStart = pseudoElementName[0] == ':' ? (pseudoElementName[1] == ':' ? 2 : 1) : 0;
    m_pseudoElementSpecifier = CSSSelector::pseudoId(CSSSelector::parsePseudoElementType(
    (pseudoElementName.substringSharingImpl(nameWithoutColonsStart))));
}

CSSComputedStyleDeclaration::~CSSComputedStyleDeclaration() = default;

void CSSComputedStyleDeclaration::ref()
{
    ++m_refCount;
}

void CSSComputedStyleDeclaration::deref()
{
    ASSERT(m_refCount);
    if (!--m_refCount)
        delete this;
}

String CSSComputedStyleDeclaration::cssText() const
{
    StringBuilder result;

    for (unsigned i = 0; i < numComputedProperties; i++) {
        if (i)
            result.append(' ');
        result.append(getPropertyName(computedProperties[i]));
        result.appendLiteral(": ");
        result.append(getPropertyValue(computedProperties[i]));
        result.append(';');
    }

    return result.toString();
}

ExceptionOr<void> CSSComputedStyleDeclaration::setCssText(const String&)
{
    return Exception { NoModificationAllowedError };
}

RefPtr<CSSPrimitiveValue> ComputedStyleExtractor::getFontSizeCSSValuePreferringKeyword()
{
    if (!m_element)
        return nullptr;

    m_element->document().updateLayoutIgnorePendingStylesheets();

    auto* style = m_element->computedStyle(m_pseudoElementSpecifier);
    if (!style)
        return nullptr;

    if (CSSValueID sizeIdentifier = style->fontDescription().keywordSizeAsIdentifier())
        return CSSValuePool::singleton().createIdentifierValue(sizeIdentifier);

    return zoomAdjustedPixelValue(style->fontDescription().computedSize(), *style);
}

bool ComputedStyleExtractor::useFixedFontDefaultSize()
{
    if (!m_element)
        return false;
    auto* style = m_element->computedStyle(m_pseudoElementSpecifier);
    if (!style)
        return false;

    return style->fontDescription().useFixedDefaultSize();
}


static CSSValueID identifierForFamily(const AtomicString& family)
{
    if (family == cursiveFamily)
        return CSSValueCursive;
    if (family == fantasyFamily)
        return CSSValueFantasy;
    if (family == monospaceFamily)
        return CSSValueMonospace;
    if (family == pictographFamily)
        return CSSValueWebkitPictograph;
    if (family == sansSerifFamily)
        return CSSValueSansSerif;
    if (family == serifFamily)
        return CSSValueSerif;
    if (family == systemUiFamily)
        return CSSValueSystemUi;
    return CSSValueInvalid;
}

static Ref<CSSPrimitiveValue> valueForFamily(const AtomicString& family)
{
    if (CSSValueID familyIdentifier = identifierForFamily(family))
        return CSSValuePool::singleton().createIdentifierValue(familyIdentifier);
    return CSSValuePool::singleton().createFontFamilyValue(family);
}

static Ref<CSSValue> renderTextDecorationFlagsToCSSValue(OptionSet<TextDecoration> textDecoration)
{
    auto& cssValuePool = CSSValuePool::singleton();
    // Blink value is ignored.
    auto list = CSSValueList::createSpaceSeparated();
    if (textDecoration & TextDecoration::Underline)
        list->append(cssValuePool.createIdentifierValue(CSSValueUnderline));
    if (textDecoration & TextDecoration::Overline)
        list->append(cssValuePool.createIdentifierValue(CSSValueOverline));
    if (textDecoration & TextDecoration::LineThrough)
        list->append(cssValuePool.createIdentifierValue(CSSValueLineThrough));
#if ENABLE(LETTERPRESS)
    if (textDecoration & TextDecoration::Letterpress)
        list->append(cssValuePool.createIdentifierValue(CSSValueWebkitLetterpress));
#endif

    if (!list->length())
        return cssValuePool.createIdentifierValue(CSSValueNone);
    return WTFMove(list);
}

static Ref<CSSValue> renderTextDecorationStyleFlagsToCSSValue(TextDecorationStyle textDecorationStyle)
{
    switch (textDecorationStyle) {
    case TextDecorationStyle::Solid:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueSolid);
    case TextDecorationStyle::Double:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueDouble);
    case TextDecorationStyle::Dotted:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueDotted);
    case TextDecorationStyle::Dashed:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueDashed);
    case TextDecorationStyle::Wavy:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueWavy);
    }

    ASSERT_NOT_REACHED();
    return CSSValuePool::singleton().createExplicitInitialValue();
}

static Ref<CSSValue> renderTextDecorationSkipFlagsToCSSValue(OptionSet<TextDecorationSkip> textDecorationSkip)
{
    // FIXME: This should probably return a CSSValueList with the set of all TextDecorationSkips.
    switch (static_cast<TextDecorationSkip>(textDecorationSkip.toRaw())) {
    case TextDecorationSkip::Auto:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueAuto);
    case TextDecorationSkip::None:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);
    case TextDecorationSkip::Ink:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueInk);
    case TextDecorationSkip::Objects:
        return CSSValuePool::singleton().createIdentifierValue(CSSValueObjects);
    }

    ASSERT_NOT_REACHED();
    return CSSValuePool::singleton().createExplicitInitialValue();
}

static Ref<CSSValue> renderEmphasisPositionFlagsToCSSValue(OptionSet<TextEmphasisPosition> textEmphasisPosition)
{
    ASSERT(!((textEmphasisPosition & TextEmphasisPosition::Over) && (textEmphasisPosition & TextEmphasisPosition::Under)));
    ASSERT(!((textEmphasisPosition & TextEmphasisPosition::Left) && (textEmphasisPosition & TextEmphasisPosition::Right)));
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createSpaceSeparated();
    if (textEmphasisPosition & TextEmphasisPosition::Over)
        list->append(cssValuePool.createIdentifierValue(CSSValueOver));
    if (textEmphasisPosition & TextEmphasisPosition::Under)
        list->append(cssValuePool.createIdentifierValue(CSSValueUnder));
    if (textEmphasisPosition & TextEmphasisPosition::Left)
        list->append(cssValuePool.createIdentifierValue(CSSValueLeft));
    if (textEmphasisPosition & TextEmphasisPosition::Right)
        list->append(cssValuePool.createIdentifierValue(CSSValueRight));
    if (!list->length())
        return cssValuePool.createIdentifierValue(CSSValueNone);
    return WTFMove(list);
}

static Ref<CSSValue> speakAsToCSSValue(OptionSet<SpeakAs> speakAs)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createSpaceSeparated();
    if (speakAs & SpeakAs::SpellOut)
        list->append(cssValuePool.createIdentifierValue(CSSValueSpellOut));
    if (speakAs & SpeakAs::Digits)
        list->append(cssValuePool.createIdentifierValue(CSSValueDigits));
    if (speakAs & SpeakAs::LiteralPunctuation)
        list->append(cssValuePool.createIdentifierValue(CSSValueLiteralPunctuation));
    if (speakAs & SpeakAs::NoPunctuation)
        list->append(cssValuePool.createIdentifierValue(CSSValueNoPunctuation));
    if (!list->length())
        return cssValuePool.createIdentifierValue(CSSValueNormal);
    return WTFMove(list);
}

static Ref<CSSValue> hangingPunctuationToCSSValue(OptionSet<HangingPunctuation> hangingPunctuation)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createSpaceSeparated();
    if (hangingPunctuation & HangingPunctuation::First)
        list->append(cssValuePool.createIdentifierValue(CSSValueFirst));
    if (hangingPunctuation & HangingPunctuation::AllowEnd)
        list->append(cssValuePool.createIdentifierValue(CSSValueAllowEnd));
    if (hangingPunctuation & HangingPunctuation::ForceEnd)
        list->append(cssValuePool.createIdentifierValue(CSSValueForceEnd));
    if (hangingPunctuation & HangingPunctuation::Last)
        list->append(cssValuePool.createIdentifierValue(CSSValueLast));
    if (!list->length())
        return cssValuePool.createIdentifierValue(CSSValueNone);
    return WTFMove(list);
}

static Ref<CSSValue> fillRepeatToCSSValue(FillRepeat xRepeat, FillRepeat yRepeat)
{
    // For backwards compatibility, if both values are equal, just return one of them. And
    // if the two values are equivalent to repeat-x or repeat-y, just return the shorthand.
    auto& cssValuePool = CSSValuePool::singleton();
    if (xRepeat == yRepeat)
        return cssValuePool.createValue(xRepeat);
    if (xRepeat == FillRepeat::Repeat && yRepeat == FillRepeat::NoRepeat)
        return cssValuePool.createIdentifierValue(CSSValueRepeatX);
    if (xRepeat == FillRepeat::NoRepeat && yRepeat == FillRepeat::Repeat)
        return cssValuePool.createIdentifierValue(CSSValueRepeatY);

    auto list = CSSValueList::createSpaceSeparated();
    list->append(cssValuePool.createValue(xRepeat));
    list->append(cssValuePool.createValue(yRepeat));
    return WTFMove(list);
}

static Ref<CSSValue> fillSourceTypeToCSSValue(MaskSourceType type)
{
    switch (type) {
    case MaskSourceType::Alpha:
        return CSSValuePool::singleton().createValue(CSSValueAlpha);
    default:
        ASSERT(type == MaskSourceType::Luminance);
        return CSSValuePool::singleton().createValue(CSSValueLuminance);
    }
}

static Ref<CSSValue> fillSizeToCSSValue(const FillSize& fillSize, const RenderStyle& style)
{
    if (fillSize.type == FillSizeType::Contain)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueContain);

    if (fillSize.type == FillSizeType::Cover)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueCover);

    if (fillSize.size.height.isAuto())
        return zoomAdjustedPixelValueForLength(fillSize.size.width, style);

    auto list = CSSValueList::createSpaceSeparated();
    list->append(zoomAdjustedPixelValueForLength(fillSize.size.width, style));
    list->append(zoomAdjustedPixelValueForLength(fillSize.size.height, style));
    return WTFMove(list);
}

static Ref<CSSValue> altTextToCSSValue(const RenderStyle& style)
{
    return CSSValuePool::singleton().createValue(style.contentAltText(), CSSPrimitiveValue::CSS_STRING);
}

static Ref<CSSValueList> contentToCSSValue(const RenderStyle& style)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createSpaceSeparated();
    for (auto* contentData = style.contentData(); contentData; contentData = contentData->next()) {
        if (is<CounterContentData>(*contentData))
            list->append(cssValuePool.createValue(downcast<CounterContentData>(*contentData).counter().identifier(), CSSPrimitiveValue::CSS_COUNTER_NAME));
        else if (is<ImageContentData>(*contentData))
            list->append(downcast<ImageContentData>(*contentData).image().cssValue());
        else if (is<TextContentData>(*contentData))
            list->append(cssValuePool.createValue(downcast<TextContentData>(*contentData).text(), CSSPrimitiveValue::CSS_STRING));
    }
    return list;
}

static Ref<CSSValue> counterToCSSValue(const RenderStyle& style, CSSPropertyID propertyID)
{
    auto* map = style.counterDirectives();
    if (!map)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    auto& cssValuePool = CSSValuePool::singleton();
    auto list = CSSValueList::createSpaceSeparated();
    for (auto& keyValue : *map) {
        list->append(cssValuePool.createValue(keyValue.key, CSSPrimitiveValue::CSS_STRING));
        double number = (propertyID == CSSPropertyCounterIncrement ? keyValue.value.incrementValue : keyValue.value.resetValue).value_or(0);
        list->append(cssValuePool.createValue(number, CSSPrimitiveValue::CSS_NUMBER));
    }
    return WTFMove(list);
}

static void logUnimplementedPropertyID(CSSPropertyID propertyID)
{
    static NeverDestroyed<HashSet<CSSPropertyID>> propertyIDSet;
    if (!propertyIDSet.get().add(propertyID).isNewEntry)
        return;

    LOG_ERROR("WebKit does not yet implement getComputedStyle for '%s'.", getPropertyName(propertyID));
}

static Ref<CSSValueList> fontFamilyListFromStyle(const RenderStyle& style)
{
    auto list = CSSValueList::createCommaSeparated();
    for (unsigned i = 0; i < style.fontCascade().familyCount(); ++i)
        list->append(valueForFamily(style.fontCascade().familyAt(i)));
    return list;
}

static Ref<CSSValue> fontFamilyFromStyle(const RenderStyle& style)
{
    if (style.fontCascade().familyCount() == 1)
        return valueForFamily(style.fontCascade().familyAt(0));
    return fontFamilyListFromStyle(style);
}

static Ref<CSSPrimitiveValue> lineHeightFromStyle(const RenderStyle& style)
{
    Length length = style.lineHeight();
    if (length.isNegative()) // If true, line-height not set; use the font's line spacing.
        return zoomAdjustedPixelValue(style.fontMetrics().floatLineSpacing(), style);
    if (length.isPercent()) {
        // This is imperfect, because it doesn't include the zoom factor and the real computation
        // for how high to be in pixels does include things like minimum font size and the zoom factor.
        // On the other hand, since font-size doesn't include the zoom factor, we really can't do
        // that here either.
        return zoomAdjustedPixelValue(static_cast<int>(length.percent() * style.fontDescription().computedSize()) / 100, style);
    }
    return zoomAdjustedPixelValue(floatValueForLength(length, 0), style);
}

static Ref<CSSPrimitiveValue> fontSizeFromStyle(const RenderStyle& style)
{
    return zoomAdjustedPixelValue(style.fontDescription().computedSize(), style);
}

Ref<CSSPrimitiveValue> ComputedStyleExtractor::fontNonKeywordWeightFromStyleValue(FontSelectionValue weight)
{
    return CSSValuePool::singleton().createValue(static_cast<float>(weight), CSSPrimitiveValue::CSS_NUMBER);
}

Ref<CSSPrimitiveValue> ComputedStyleExtractor::fontWeightFromStyleValue(FontSelectionValue weight)
{
    if (auto value = fontWeightKeyword(weight))
        return CSSValuePool::singleton().createIdentifierValue(value.value());
    return fontNonKeywordWeightFromStyleValue(weight);
}

static Ref<CSSPrimitiveValue> fontWeightFromStyle(const RenderStyle& style)
{
    return ComputedStyleExtractor::fontWeightFromStyleValue(style.fontDescription().weight());
}

Ref<CSSPrimitiveValue> ComputedStyleExtractor::fontNonKeywordStretchFromStyleValue(FontSelectionValue stretch)
{
    return CSSValuePool::singleton().createValue(static_cast<float>(stretch), CSSPrimitiveValue::CSS_PERCENTAGE);
}

Ref<CSSPrimitiveValue> ComputedStyleExtractor::fontStretchFromStyleValue(FontSelectionValue stretch)
{
    if (auto keyword = fontStretchKeyword(stretch))
        return CSSValuePool::singleton().createIdentifierValue(keyword.value());
    return fontNonKeywordStretchFromStyleValue(stretch);
}

static Ref<CSSPrimitiveValue> fontStretchFromStyle(const RenderStyle& style)
{
    return ComputedStyleExtractor::fontStretchFromStyleValue(style.fontDescription().stretch());
}

Ref<CSSFontStyleValue> ComputedStyleExtractor::fontNonKeywordStyleFromStyleValue(FontSelectionValue italic)
{
    return CSSFontStyleValue::create(CSSValuePool::singleton().createIdentifierValue(CSSValueOblique), CSSValuePool::singleton().createValue(static_cast<float>(italic), CSSPrimitiveValue::CSS_DEG));
}

Ref<CSSFontStyleValue> ComputedStyleExtractor::fontStyleFromStyleValue(std::optional<FontSelectionValue> italic, FontStyleAxis fontStyleAxis)
{
    if (auto keyword = fontStyleKeyword(italic, fontStyleAxis))
        return CSSFontStyleValue::create(CSSValuePool::singleton().createIdentifierValue(keyword.value()));
    return fontNonKeywordStyleFromStyleValue(italic.value());
}

static Ref<CSSFontStyleValue> fontStyleFromStyle(const RenderStyle& style)
{
    return ComputedStyleExtractor::fontStyleFromStyleValue(style.fontDescription().italic(), style.fontDescription().fontStyleAxis());
}

static Ref<CSSValue> fontVariantFromStyle(const RenderStyle& style)
{
    if (style.fontDescription().variantSettings().isAllNormal())
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNormal);

    auto list = CSSValueList::createSpaceSeparated();

    switch (style.fontDescription().variantCommonLigatures()) {
    case FontVariantLigatures::Normal:
        break;
    case FontVariantLigatures::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueCommonLigatures));
        break;
    case FontVariantLigatures::No:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueNoCommonLigatures));
        break;
    }

    switch (style.fontDescription().variantDiscretionaryLigatures()) {
    case FontVariantLigatures::Normal:
        break;
    case FontVariantLigatures::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueDiscretionaryLigatures));
        break;
    case FontVariantLigatures::No:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueNoDiscretionaryLigatures));
        break;
    }

    switch (style.fontDescription().variantHistoricalLigatures()) {
    case FontVariantLigatures::Normal:
        break;
    case FontVariantLigatures::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueHistoricalLigatures));
        break;
    case FontVariantLigatures::No:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueNoHistoricalLigatures));
        break;
    }

    switch (style.fontDescription().variantContextualAlternates()) {
    case FontVariantLigatures::Normal:
        break;
    case FontVariantLigatures::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueContextual));
        break;
    case FontVariantLigatures::No:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueNoContextual));
        break;
    }

    switch (style.fontDescription().variantPosition()) {
    case FontVariantPosition::Normal:
        break;
    case FontVariantPosition::Subscript:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSub));
        break;
    case FontVariantPosition::Superscript:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSuper));
        break;
    }

    switch (style.fontDescription().variantCaps()) {
    case FontVariantCaps::Normal:
        break;
    case FontVariantCaps::Small:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSmallCaps));
        break;
    case FontVariantCaps::AllSmall:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueAllSmallCaps));
        break;
    case FontVariantCaps::Petite:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValuePetiteCaps));
        break;
    case FontVariantCaps::AllPetite:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueAllPetiteCaps));
        break;
    case FontVariantCaps::Unicase:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueUnicase));
        break;
    case FontVariantCaps::Titling:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueTitlingCaps));
        break;
    }

    switch (style.fontDescription().variantNumericFigure()) {
    case FontVariantNumericFigure::Normal:
        break;
    case FontVariantNumericFigure::LiningNumbers:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueLiningNums));
        break;
    case FontVariantNumericFigure::OldStyleNumbers:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueOldstyleNums));
        break;
    }

    switch (style.fontDescription().variantNumericSpacing()) {
    case FontVariantNumericSpacing::Normal:
        break;
    case FontVariantNumericSpacing::ProportionalNumbers:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueProportionalNums));
        break;
    case FontVariantNumericSpacing::TabularNumbers:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueTabularNums));
        break;
    }

    switch (style.fontDescription().variantNumericFraction()) {
    case FontVariantNumericFraction::Normal:
        break;
    case FontVariantNumericFraction::DiagonalFractions:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueDiagonalFractions));
        break;
    case FontVariantNumericFraction::StackedFractions:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueStackedFractions));
        break;
    }

    switch (style.fontDescription().variantNumericOrdinal()) {
    case FontVariantNumericOrdinal::Normal:
        break;
    case FontVariantNumericOrdinal::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueOrdinal));
        break;
    }

    switch (style.fontDescription().variantNumericSlashedZero()) {
    case FontVariantNumericSlashedZero::Normal:
        break;
    case FontVariantNumericSlashedZero::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSlashedZero));
        break;
    }

    switch (style.fontDescription().variantAlternates()) {
    case FontVariantAlternates::Normal:
        break;
    case FontVariantAlternates::HistoricalForms:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueHistoricalForms));
        break;
    }

    switch (style.fontDescription().variantEastAsianVariant()) {
    case FontVariantEastAsianVariant::Normal:
        break;
    case FontVariantEastAsianVariant::Jis78:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueJis78));
        break;
    case FontVariantEastAsianVariant::Jis83:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueJis83));
        break;
    case FontVariantEastAsianVariant::Jis90:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueJis90));
        break;
    case FontVariantEastAsianVariant::Jis04:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueJis04));
        break;
    case FontVariantEastAsianVariant::Simplified:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSimplified));
        break;
    case FontVariantEastAsianVariant::Traditional:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueTraditional));
        break;
    }

    switch (style.fontDescription().variantEastAsianWidth()) {
    case FontVariantEastAsianWidth::Normal:
        break;
    case FontVariantEastAsianWidth::Full:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueFullWidth));
        break;
    case FontVariantEastAsianWidth::Proportional:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueProportionalWidth));
        break;
    }

    switch (style.fontDescription().variantEastAsianRuby()) {
    case FontVariantEastAsianRuby::Normal:
        break;
    case FontVariantEastAsianRuby::Yes:
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueRuby));
        break;
    }

    return WTFMove(list);
}

static Ref<CSSValue> fontSynthesisFromStyle(const RenderStyle& style)
{
    if (style.fontDescription().fontSynthesis() == FontSynthesisNone)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    auto list = CSSValueList::createSpaceSeparated();
    if (style.fontDescription().fontSynthesis() & FontSynthesisStyle)
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueStyle));
    if (style.fontDescription().fontSynthesis() & FontSynthesisWeight)
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueWeight));
    if (style.fontDescription().fontSynthesis() & FontSynthesisSmallCaps)
        list->append(CSSValuePool::singleton().createIdentifierValue(CSSValueSmallCaps));
    return WTFMove(list);
}

typedef const Length& (RenderStyle::*RenderStyleLengthGetter)() const;
typedef LayoutUnit (RenderBoxModelObject::*RenderBoxComputedCSSValueGetter)() const;

template<RenderStyleLengthGetter lengthGetter, RenderBoxComputedCSSValueGetter computedCSSValueGetter>
static RefPtr<CSSValue> zoomAdjustedPaddingOrMarginPixelValue(const RenderStyle& style, RenderObject* renderer)
{
    Length unzoomzedLength = (style.*lengthGetter)();
    if (!is<RenderBox>(renderer) || unzoomzedLength.isFixed())
        return zoomAdjustedPixelValueForLength(unzoomzedLength, style);
    return zoomAdjustedPixelValue((downcast<RenderBox>(*renderer).*computedCSSValueGetter)(), style);
}

template<RenderStyleLengthGetter lengthGetter>
static bool paddingOrMarginIsRendererDependent(const RenderStyle* style, RenderObject* renderer)
{
    return renderer && style && renderer->isBox() && !(style->*lengthGetter)().isFixed();
}

static bool positionOffsetValueIsRendererDependent(const RenderStyle* style, RenderObject* renderer)
{
    return renderer && style && renderer->isBox();
}

static CSSValueID convertToPageBreak(BreakBetween value)
{
    if (value == BreakBetween::Page || value == BreakBetween::LeftPage || value == BreakBetween::RightPage
        || value == BreakBetween::RectoPage || value == BreakBetween::VersoPage)
        return CSSValueAlways; // CSS 2.1 allows us to map these to always.
    if (value == BreakBetween::Avoid || value == BreakBetween::AvoidPage)
        return CSSValueAvoid;
    return CSSValueAuto;
}

static CSSValueID convertToColumnBreak(BreakBetween value)
{
    if (value == BreakBetween::Column)
        return CSSValueAlways;
    if (value == BreakBetween::Avoid || value == BreakBetween::AvoidColumn)
        return CSSValueAvoid;
    return CSSValueAuto;
}

static CSSValueID convertToPageBreak(BreakInside value)
{
    if (value == BreakInside::Avoid || value == BreakInside::AvoidPage)
        return CSSValueAvoid;
    return CSSValueAuto;
}

static CSSValueID convertToColumnBreak(BreakInside value)
{
    if (value == BreakInside::Avoid || value == BreakInside::AvoidColumn)
        return CSSValueAvoid;
    return CSSValueAuto;
}

static inline bool isNonReplacedInline(RenderObject& renderer)
{
    return renderer.isInline() && !renderer.isReplaced();
}

static bool isLayoutDependent(CSSPropertyID propertyID, const RenderStyle* style, RenderObject* renderer)
{
    switch (propertyID) {
    case CSSPropertyTop:
    case CSSPropertyBottom:
    case CSSPropertyLeft:
    case CSSPropertyRight:
        return positionOffsetValueIsRendererDependent(style, renderer);
    case CSSPropertyWidth:
    case CSSPropertyHeight:
    case CSSPropertyInlineSize:
    case CSSPropertyBlockSize:
        return renderer && !renderer->isRenderSVGModelObject() && !isNonReplacedInline(*renderer);
    case CSSPropertyPerspectiveOrigin:
    case CSSPropertyTransformOrigin:
    case CSSPropertyTransform:
    case CSSPropertyFilter: // Why are filters layout-dependent?
#if ENABLE(FILTERS_LEVEL_2)
    case CSSPropertyWebkitBackdropFilter: // Ditto for backdrop-filter.
#endif
        return true;
    case CSSPropertyMargin: {
        if (!renderer || !renderer->isBox())
            return false;
        return !(style && style->marginTop().isFixed() && style->marginRight().isFixed()
            && style->marginBottom().isFixed() && style->marginLeft().isFixed());
    }
    case CSSPropertyMarginTop:
        return paddingOrMarginIsRendererDependent<&RenderStyle::marginTop>(style, renderer);
    case CSSPropertyMarginRight:
        return paddingOrMarginIsRendererDependent<&RenderStyle::marginRight>(style, renderer);
    case CSSPropertyMarginBottom:
        return paddingOrMarginIsRendererDependent<&RenderStyle::marginBottom>(style, renderer);
    case CSSPropertyMarginLeft:
        return paddingOrMarginIsRendererDependent<&RenderStyle::marginLeft>(style, renderer);
    case CSSPropertyPadding: {
        if (!renderer || !renderer->isBox())
            return false;
        return !(style && style->paddingTop().isFixed() && style->paddingRight().isFixed()
            && style->paddingBottom().isFixed() && style->paddingLeft().isFixed());
    }
    case CSSPropertyPaddingTop:
        return paddingOrMarginIsRendererDependent<&RenderStyle::paddingTop>(style, renderer);
    case CSSPropertyPaddingRight:
        return paddingOrMarginIsRendererDependent<&RenderStyle::paddingRight>(style, renderer);
    case CSSPropertyPaddingBottom:
        return paddingOrMarginIsRendererDependent<&RenderStyle::paddingBottom>(style, renderer);
    case CSSPropertyPaddingLeft:
        return paddingOrMarginIsRendererDependent<&RenderStyle::paddingLeft>(style, renderer);
    case CSSPropertyGridTemplateColumns:
    case CSSPropertyGridTemplateRows:
    case CSSPropertyGridTemplate:
    case CSSPropertyGrid:
        return renderer && renderer->isRenderGrid();
    default:
        return false;
    }
}

Element* ComputedStyleExtractor::styledElement() const
{
    if (!m_element)
        return nullptr;
    PseudoElement* pseudoElement;
    if (m_pseudoElementSpecifier == PseudoId::Before && (pseudoElement = m_element->beforePseudoElement()))
        return pseudoElement;
    if (m_pseudoElementSpecifier == PseudoId::After && (pseudoElement = m_element->afterPseudoElement()))
        return pseudoElement;
    return m_element.get();
}

RenderElement* ComputedStyleExtractor::styledRenderer() const
{
    auto* element = styledElement();
    if (!element)
        return nullptr;
    if (m_pseudoElementSpecifier != PseudoId::None && element == m_element.get())
        return nullptr;
    if (element->hasDisplayContents())
        return nullptr;
    return element->renderer();
}

static bool isImplicitlyInheritedGridOrFlexProperty(CSSPropertyID propertyID)
{
    // It would be nice if grid and flex worked within normal CSS mechanisms and not invented their own inheritance system.
    switch (propertyID) {
    case CSSPropertyAlignSelf:
    case CSSPropertyJustifySelf:
    case CSSPropertyJustifyItems:
    // FIXME: In StyleResolver::adjustRenderStyle z-index is adjusted based on the parent display property for grid/flex.
    case CSSPropertyZIndex:
        return true;
    default:
        return false;
    }
}

// In CSS 2.1 the returned object should actually contain the "used values"
// rather then the "computed values" (despite the name saying otherwise).
//
// See;
// http://www.w3.org/TR/CSS21/cascade.html#used-value
// http://www.w3.org/TR/DOM-Level-2-Style/css.html#CSS-CSSStyleDeclaration
// https://developer.mozilla.org/en-US/docs/Web/API/Window/getComputedStyle#Notes
RefPtr<CSSValue> CSSComputedStyleDeclaration::getPropertyCSSValue(CSSPropertyID propertyID, EUpdateLayout updateLayout) const
{
    return ComputedStyleExtractor(m_element.ptr(), m_allowVisitedStyle, m_pseudoElementSpecifier).propertyValue(propertyID, updateLayout);
}

Ref<MutableStyleProperties> CSSComputedStyleDeclaration::copyProperties() const
{
    return ComputedStyleExtractor(m_element.ptr(), m_allowVisitedStyle, m_pseudoElementSpecifier).copyProperties();
}

static inline bool hasValidStyleForProperty(Element& element, CSSPropertyID propertyID)
{
    if (element.styleValidity() != Style::Validity::Valid)
        return false;
    if (element.document().hasPendingForcedStyleRecalc())
        return false;
    if (!element.document().childNeedsStyleRecalc())
        return true;

    bool isInherited = CSSProperty::isInheritedProperty(propertyID) || isImplicitlyInheritedGridOrFlexProperty(propertyID);
    bool maybeExplicitlyInherited = !isInherited;

    const auto* currentElement = &element;
    for (auto& ancestor : composedTreeAncestors(element)) {
        if (ancestor.styleValidity() >= Style::Validity::SubtreeInvalid)
            return false;

        if (maybeExplicitlyInherited) {
            auto* style = currentElement->renderStyle();
            maybeExplicitlyInherited = !style || style->hasExplicitlyInheritedProperties();
        }

        if ((isInherited || maybeExplicitlyInherited) && ancestor.styleValidity() == Style::Validity::ElementInvalid)
            return false;

        if (ancestor.directChildNeedsStyleRecalc() && currentElement->styleIsAffectedByPreviousSibling())
            return false;

        currentElement = &ancestor;
    }

    return true;
}

static bool updateStyleIfNeededForProperty(Element& element, CSSPropertyID propertyID)
{
    auto& document = element.document();

    document.styleScope().flushPendingUpdate();

    if (hasValidStyleForProperty(element, propertyID))
        return false;

    document.updateStyleIfNeeded();
    return true;
}

static inline const RenderStyle* computeRenderStyleForProperty(Element& element, PseudoId pseudoElementSpecifier, CSSPropertyID propertyID, std::unique_ptr<RenderStyle>& ownedStyle)
{
    auto* renderer = element.renderer();

    if (renderer && renderer->isComposited() && CSSAnimationController::supportsAcceleratedAnimationOfProperty(propertyID)) {
        if (auto timeline = element.document().existingTimeline())
            ownedStyle = timeline->animatedStyleForRenderer(*renderer);
        else
            ownedStyle = renderer->animation().animatedStyleForRenderer(*renderer);
        if (pseudoElementSpecifier != PseudoId::None && !element.isPseudoElement()) {
            // FIXME: This cached pseudo style will only exist if the animation has been run at least once.
            return ownedStyle->getCachedPseudoStyle(pseudoElementSpecifier);
        }
        return ownedStyle.get();
    }

    return element.computedStyle(element.isPseudoElement() ? PseudoId::None : pseudoElementSpecifier);
}

static Ref<CSSValue> shapePropertyValue(const RenderStyle& style, const ShapeValue* shapeValue)
{
    if (!shapeValue)
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);

    if (shapeValue->type() == ShapeValue::Type::Box)
        return CSSValuePool::singleton().createValue(shapeValue->cssBox());

    if (shapeValue->type() == ShapeValue::Type::Image) {
        if (shapeValue->image())
            return shapeValue->image()->cssValue();
        return CSSValuePool::singleton().createIdentifierValue(CSSValueNone);
    }

    ASSERT(shapeValue->type() == ShapeValue::Type::Shape);

    auto list = CSSValueList::createSpaceSeparated();
    list->append(valueForBasicShape(style, *shapeValue->shape()));
    if (shapeValue->cssBox() != CSSBoxType::BoxMissing)
        list->append(CSSValuePool::singleton().createValue(shapeValue->cssBox()));
    return WTFMove(list);
}

static Ref<CSSValueList> valueForItemPositionWithOverflowAlignment(const StyleSelfAlignmentData& data)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto result = CSSValueList::createSpaceSeparated();
    if (data.positionType() == ItemPositionType::Legacy)
        result->append(cssValuePool.createIdentifierValue(CSSValueLegacy));
    if (data.position() == ItemPosition::Baseline)
        result->append(cssValuePool.createIdentifierValue(CSSValueBaseline));
    else if (data.position() == ItemPosition::LastBaseline) {
        result->append(cssValuePool.createIdentifierValue(CSSValueLast));
        result->append(cssValuePool.createIdentifierValue(CSSValueBaseline));
    } else {
        if (data.position() >= ItemPosition::Center && data.overflow() != OverflowAlignment::Default)
            result->append(cssValuePool.createValue(data.overflow()));
        if (data.position() == ItemPosition::Legacy)
            result->append(cssValuePool.createIdentifierValue(CSSValueNormal));
        else
            result->append(cssValuePool.createValue(data.position()));
    }
    ASSERT(result->length() <= 2);
    return result;
}

static Ref<CSSValueList> valueForContentPositionAndDistributionWithOverflowAlignment(const StyleContentAlignmentData& data)
{
    auto& cssValuePool = CSSValuePool::singleton();
    auto result = CSSValueList::createSpaceSeparated();
    // Handle content-distribution values
    if (data.distribution() != ContentDistribution::Default)
        result->append(cssValuePool.createValue(data.distribution()));

    // Handle content-position values (either as fallback or actual value)
    switch (data.position()) {
    case ContentPosition::Normal:
        // Handle 'normal' value, not valid as content-distribution fallback.
        if (data.distribution() == ContentDistribution::Default)
            result->append(cssValuePool.createIdentifierValue(CSSValueNormal));
        break;
    case ContentPosition::LastBaseline:
        result->append(cssValuePool.createIdentifierValue(CSSValueLast));
        result->append(cssValuePool.createIdentifierValue(CSSValueBaseline));
        break;
    default:
        // Handle overflow-alignment (only allowed for content-position values)
        if ((data.position() >= ContentPosition::Center || data.distribution() != ContentDistribution::Default) && data.overflow() != OverflowAlignment::Default)
            result->append(cssValuePool.createValue(data.overflow()));
        result->append(cssValuePool.createValue(data.position()));
    }

    ASSERT(result->length() > 0);
    ASSERT(result->length() <= 3);
    return result;
}

static Ref<CSSValue> paintOrder(PaintOrder paintOrder)
{
    if (paintOrder == PaintOrder::Normal)
        return CSSPrimitiveValue::createIdentifier(CSSValueNormal);

    auto paintOrderList = CSSValueList::createSpaceSeparated();
    switch (paintOrder) {
    case PaintOrder::Normal:
        ASSERT_NOT_REACHED();
        break;
    case PaintOrder::Fill:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueFill));
        break;
    case PaintOrder::FillMarkers:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueFill));
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueMarkers));
        break;
    case PaintOrder::Stroke:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueStroke));
        break;
    case PaintOrder::StrokeMarkers:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueStroke));
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueMarkers));
        break;
    case PaintOrder::Markers:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueMarkers));
        break;
    case PaintOrder::MarkersStroke:
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueMarkers));
        paintOrderList->append(CSSPrimitiveValue::createIdentifier(CSSValueStroke));
        break;
    }
    return WTFMove(paintOrderList);
}

inline static bool isFlexOrGrid(ContainerNode* element)
{
    return element && element->computedStyle() && element->computedStyle()->isDisplayFlexibleOrGridBox();
}

RefPtr<CSSValue> ComputedStyleExtractor::customPropertyValue(const String& propertyName)
{
    Element* styledElement = this->styledElement();
    if (!styledElement)
        return nullptr;

    if (updateStyleIfNeededForProperty(*styledElement, CSSPropertyCustom)) {
        // Style update may change styledElement() to PseudoElement or back.
        styledElement = this->styledElement();
    }

    std::unique_ptr<RenderStyle> ownedStyle;
    auto* style = computeRenderStyleForProperty(*styledElement, m_pseudoElementSpecifier, CSSPropertyCustom, ownedStyle);
    if (!style)
        return nullptr;

    return style->customProperties().get(propertyName);
}

String ComputedStyleExtractor::customPropertyText(const String& propertyName)
{
    RefPtr<CSSValue> propertyValue = customPropertyValue(propertyName);
    return propertyValue ? propertyValue->cssText() : emptyString();
}

static Ref<CSSFontValue> fontShorthandValueForSelectionProperties(const FontDescription& fontDescription)
{
    auto computedFont = CSSFontValue::create();

    auto variantCaps = fontDescription.variantCaps();
    if (variantCaps == FontVariantCaps::Small)
        computedFont->variant = CSSValuePool::singleton().createIdentifierValue(CSSValueSmallCaps);
    else if (variantCaps == FontVariantCaps::Normal)
        computedFont->variant = CSSValuePool::singleton().createIdentifierValue(CSSValueNormal);
    else
        return CSSFontValue::create();

    auto weight = fontDescription.weight();
    if (auto value = fontWeightKeyword(weight))
        computedFont->weight = CSSValuePool::singleton().createIdentifierValue(value.value());
    else if (isCSS21Weight(weight))
        computedFont->weight = CSSValuePool::singleton().createValue(static_cast<float>(weight), CSSPrimitiveValue::CSS_NUMBER);
    else
        return CSSFontValue::create();

    if (auto keyword = fontStretchKeyword(fontDescription.stretch()))
        computedFont->stretch = CSSValuePool::singleton().createIdentifierValue(keyword.value());
    else
        return CSSFontValue::create();

    if (auto italic = fontStyleKeyword(fontDescription.italic(), fontDescription.fontStyleAxis()))
        computedFont->style = CSSFontStyleValue::create(CSSValuePool::singleton().createIdentifierValue(italic.value()));
    else
        return CSSFontValue::create();

    return computedFont;
}

RefPtr<CSSValue> ComputedStyleExtractor::propertyValue(CSSPropertyID propertyID, EUpdateLayout updateLayout)
{
    auto* styledElement = this->styledElement();
    if (!styledElement)
        return nullptr;

    std::unique_ptr<RenderStyle> ownedStyle;
    const RenderStyle* style = nullptr;
    RenderElement* renderer = nullptr;
    bool forceFullLayout = false;
    if (updateLayout) {
        Document& document = m_element->document();

        if (updateStyleIfNeededForProperty(*styledElement, propertyID)) {
            // Style update may change styledElement() to PseudoElement or back.
            styledElement = this->styledElement();
        }
        renderer = styledRenderer();

        if (propertyID == CSSPropertyDisplay && !renderer && is<SVGElement>(*styledElement) && !downcast<SVGElement>(*styledElement).isValid())
            return nullptr;

        style = computeRenderStyleForProperty(*styledElement, m_pseudoElementSpecifier, propertyID, ownedStyle);

        // FIXME: Some of these cases could be narrowed down or optimized better.
        forceFullLayout = isLayoutDependent(propertyID, style, renderer)
            || styledElement->isInShadowTree()
            || (document.styleScope().resolverIfExists() && document.styleScope().resolverIfExists()->hasViewportDependentMediaQueries() && document.ownerElement());

        if (forceFullLayout) {
            document.updateLayoutIgnorePendingStylesheets();
            styledElement = this->styledElement();
        }
    }

    if (!updateLayout || forceFullLayout) {
        style = computeRenderStyleForProperty(*styledElement, m_pseudoElementSpecifier, propertyID, ownedStyle);
        renderer = styledRenderer();
    }

    if (!style)
        return nullptr;

    return valueForPropertyinStyle(*style, propertyID, renderer);
}

RefPtr<CSSValue> ComputedStyleExtractor::valueForPropertyinStyle(const RenderStyle& style, CSSPropertyID propertyID, RenderElement* renderer)
{
    auto& cssValuePool = CSSValuePool::singleton();
    propertyID = CSSProperty::resolveDirectionAwareProperty(propertyID, style.direction(), style.writingMode());

    switch (propertyID) {
        case CSSPropertyInvalid:
            break;

        case CSSPropertyBackgroundColor:
            return cssValuePool.createColorValue(m_allowVisitedStyle? style.visitedDependentColor(CSSPropertyBackgroundColor) : style.backgroundColor());
        case CSSPropertyBackgroundImage:
        case CSSPropertyWebkitMaskImage: {
            auto& layers = propertyID == CSSPropertyWebkitMaskImage ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next()) {
                if (layers.image())
                    return layers.image()->cssValue();
                return cssValuePool.createIdentifierValue(CSSValueNone);
            }
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next()) {
                if (currLayer->image())
                    list->append(currLayer->image()->cssValue());
                else
                    list->append(cssValuePool.createIdentifierValue(CSSValueNone));
            }
            return WTFMove(list);
        }
        case CSSPropertyBackgroundSize:
        case CSSPropertyWebkitBackgroundSize:
        case CSSPropertyWebkitMaskSize: {
            auto& layers = propertyID == CSSPropertyWebkitMaskSize ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return fillSizeToCSSValue(layers.size(), style);
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(fillSizeToCSSValue(currLayer->size(), style));
            return WTFMove(list);
        }
        case CSSPropertyBackgroundRepeat:
        case CSSPropertyWebkitMaskRepeat: {
            auto& layers = propertyID == CSSPropertyWebkitMaskRepeat ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return fillRepeatToCSSValue(layers.repeatX(), layers.repeatY());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(fillRepeatToCSSValue(currLayer->repeatX(), currLayer->repeatY()));
            return WTFMove(list);
        }
        case CSSPropertyWebkitMaskSourceType: {
            auto& layers = style.maskLayers();
            if (!layers.next())
                return fillSourceTypeToCSSValue(layers.maskSourceType());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(fillSourceTypeToCSSValue(currLayer->maskSourceType()));
            return WTFMove(list);
        }
        case CSSPropertyWebkitBackgroundComposite:
        case CSSPropertyWebkitMaskComposite: {
            auto& layers = propertyID == CSSPropertyWebkitMaskComposite ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return cssValuePool.createValue(layers.composite());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(currLayer->composite()));
            return WTFMove(list);
        }
        case CSSPropertyBackgroundAttachment: {
            auto& layers = style.backgroundLayers();
            if (!layers.next())
                return cssValuePool.createValue(layers.attachment());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(currLayer->attachment()));
            return WTFMove(list);
        }
        case CSSPropertyBackgroundClip:
        case CSSPropertyBackgroundOrigin:
        case CSSPropertyWebkitBackgroundClip:
        case CSSPropertyWebkitBackgroundOrigin:
        case CSSPropertyWebkitMaskClip:
        case CSSPropertyWebkitMaskOrigin: {
            auto& layers = (propertyID == CSSPropertyWebkitMaskClip || propertyID == CSSPropertyWebkitMaskOrigin) ? style.maskLayers() : style.backgroundLayers();
            bool isClip = propertyID == CSSPropertyBackgroundClip || propertyID == CSSPropertyWebkitBackgroundClip || propertyID == CSSPropertyWebkitMaskClip;
            if (!layers.next())
                return cssValuePool.createValue(isClip ? layers.clip() : layers.origin());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(isClip ? currLayer->clip() : currLayer->origin()));
            return WTFMove(list);
        }
        case CSSPropertyBackgroundPosition:
        case CSSPropertyWebkitMaskPosition: {
            auto& layers = propertyID == CSSPropertyWebkitMaskPosition ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return createPositionListForLayer(propertyID, layers, style);

            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(createPositionListForLayer(propertyID, *currLayer, style));
            return WTFMove(list);
        }
        case CSSPropertyBackgroundPositionX:
        case CSSPropertyWebkitMaskPositionX: {
            auto& layers = propertyID == CSSPropertyWebkitMaskPositionX ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return cssValuePool.createValue(layers.xPosition());

            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(currLayer->xPosition()));

            return WTFMove(list);
        }
        case CSSPropertyBackgroundPositionY:
        case CSSPropertyWebkitMaskPositionY: {
            auto& layers = propertyID == CSSPropertyWebkitMaskPositionY ? style.maskLayers() : style.backgroundLayers();
            if (!layers.next())
                return cssValuePool.createValue(layers.yPosition());

            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(currLayer->yPosition()));

            return WTFMove(list);
        }
        case CSSPropertyBorderCollapse:
            if (style.borderCollapse() == BorderCollapse::Collapse)
                return cssValuePool.createIdentifierValue(CSSValueCollapse);
            return cssValuePool.createIdentifierValue(CSSValueSeparate);
        case CSSPropertyBorderSpacing: {
            auto list = CSSValueList::createSpaceSeparated();
            list->append(zoomAdjustedPixelValue(style.horizontalBorderSpacing(), style));
            list->append(zoomAdjustedPixelValue(style.verticalBorderSpacing(), style));
            return WTFMove(list);
        }
        case CSSPropertyWebkitBorderHorizontalSpacing:
            return zoomAdjustedPixelValue(style.horizontalBorderSpacing(), style);
        case CSSPropertyWebkitBorderVerticalSpacing:
            return zoomAdjustedPixelValue(style.verticalBorderSpacing(), style);
        case CSSPropertyBorderImageSource:
            if (style.borderImageSource())
                return style.borderImageSource()->cssValue();
            return cssValuePool.createIdentifierValue(CSSValueNone);
        case CSSPropertyBorderTopColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyBorderTopColor)) : currentColorOrValidColor(&style, style.borderTopColor());
        case CSSPropertyBorderRightColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyBorderRightColor)) : currentColorOrValidColor(&style, style.borderRightColor());
        case CSSPropertyBorderBottomColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyBorderBottomColor)) : currentColorOrValidColor(&style, style.borderBottomColor());
        case CSSPropertyBorderLeftColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyBorderLeftColor)) : currentColorOrValidColor(&style, style.borderLeftColor());
        case CSSPropertyBorderTopStyle:
            return cssValuePool.createValue(style.borderTopStyle());
        case CSSPropertyBorderRightStyle:
            return cssValuePool.createValue(style.borderRightStyle());
        case CSSPropertyBorderBottomStyle:
            return cssValuePool.createValue(style.borderBottomStyle());
        case CSSPropertyBorderLeftStyle:
            return cssValuePool.createValue(style.borderLeftStyle());
        case CSSPropertyBorderTopWidth:
            return zoomAdjustedPixelValue(style.borderTopWidth(), style);
        case CSSPropertyBorderRightWidth:
            return zoomAdjustedPixelValue(style.borderRightWidth(), style);
        case CSSPropertyBorderBottomWidth:
            return zoomAdjustedPixelValue(style.borderBottomWidth(), style);
        case CSSPropertyBorderLeftWidth:
            return zoomAdjustedPixelValue(style.borderLeftWidth(), style);
        case CSSPropertyBottom:
            return positionOffsetValue(style, CSSPropertyBottom, renderer);
        case CSSPropertyWebkitBoxAlign:
            return cssValuePool.createValue(style.boxAlign());
#if ENABLE(CSS_BOX_DECORATION_BREAK)
        case CSSPropertyWebkitBoxDecorationBreak:
            if (style.boxDecorationBreak() == BoxDecorationBreak::Slice)
                return cssValuePool.createIdentifierValue(CSSValueSlice);
        return cssValuePool.createIdentifierValue(CSSValueClone);
#endif
        case CSSPropertyWebkitBoxDirection:
            return cssValuePool.createValue(style.boxDirection());
        case CSSPropertyWebkitBoxFlex:
            return cssValuePool.createValue(style.boxFlex(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitBoxFlexGroup:
            return cssValuePool.createValue(style.boxFlexGroup(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitBoxLines:
            return cssValuePool.createValue(style.boxLines());
        case CSSPropertyWebkitBoxOrdinalGroup:
            return cssValuePool.createValue(style.boxOrdinalGroup(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitBoxOrient:
            return cssValuePool.createValue(style.boxOrient());
        case CSSPropertyWebkitBoxPack:
            return cssValuePool.createValue(style.boxPack());
        case CSSPropertyWebkitBoxReflect:
            return valueForReflection(style.boxReflect(), style);
        case CSSPropertyBoxShadow:
        case CSSPropertyWebkitBoxShadow:
            return valueForShadow(style.boxShadow(), propertyID, style);
        case CSSPropertyCaptionSide:
            return cssValuePool.createValue(style.captionSide());
        case CSSPropertyCaretColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyCaretColor)) : currentColorOrValidColor(&style, style.caretColor());
        case CSSPropertyClear:
            return cssValuePool.createValue(style.clear());
        case CSSPropertyColor:
            return cssValuePool.createColorValue(m_allowVisitedStyle ? style.visitedDependentColor(CSSPropertyColor) : style.color());
        case CSSPropertyWebkitPrintColorAdjust:
            return cssValuePool.createValue(style.printColorAdjust());
        case CSSPropertyWebkitColumnAxis:
            return cssValuePool.createValue(style.columnAxis());
        case CSSPropertyColumnCount:
            if (style.hasAutoColumnCount())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.columnCount(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyColumnFill:
            return cssValuePool.createValue(style.columnFill());
        case CSSPropertyColumnGap:
            if (style.columnGap().isNormal())
                return cssValuePool.createIdentifierValue(CSSValueNormal);
            return zoomAdjustedPixelValueForLength(style.columnGap().length(), style);
        case CSSPropertyRowGap:
            if (style.rowGap().isNormal())
                return cssValuePool.createIdentifierValue(CSSValueNormal);
            return zoomAdjustedPixelValueForLength(style.rowGap().length(), style);
        case CSSPropertyWebkitColumnProgression:
            return cssValuePool.createValue(style.columnProgression());
        case CSSPropertyColumnRuleColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyOutlineColor)) : currentColorOrValidColor(&style, style.columnRuleColor());
        case CSSPropertyColumnRuleStyle:
            return cssValuePool.createValue(style.columnRuleStyle());
        case CSSPropertyColumnRuleWidth:
            return zoomAdjustedPixelValue(style.columnRuleWidth(), style);
        case CSSPropertyColumnSpan:
            return cssValuePool.createIdentifierValue(style.columnSpan() == ColumnSpan::All ? CSSValueAll : CSSValueNone);
        case CSSPropertyWebkitColumnBreakAfter:
            return cssValuePool.createValue(convertToColumnBreak(style.breakAfter()));
        case CSSPropertyWebkitColumnBreakBefore:
            return cssValuePool.createValue(convertToColumnBreak(style.breakBefore()));
        case CSSPropertyWebkitColumnBreakInside:
            return cssValuePool.createValue(convertToColumnBreak(style.breakInside()));
        case CSSPropertyColumnWidth:
            if (style.hasAutoColumnWidth())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return zoomAdjustedPixelValue(style.columnWidth(), style);
        case CSSPropertyTabSize:
            return cssValuePool.createValue(style.tabSize(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyCursor: {
            RefPtr<CSSValueList> list;
            auto* cursors = style.cursors();
            if (cursors && cursors->size() > 0) {
                list = CSSValueList::createCommaSeparated();
                for (unsigned i = 0; i < cursors->size(); ++i)
                    if (StyleImage* image = cursors->at(i).image())
                        list->append(image->cssValue());
            }
            auto value = cssValuePool.createValue(style.cursor());
            if (list) {
                list->append(WTFMove(value));
                return list;
            }
            return WTFMove(value);
        }
#if ENABLE(CURSOR_VISIBILITY)
        case CSSPropertyWebkitCursorVisibility:
            return cssValuePool.createValue(style.cursorVisibility());
#endif
        case CSSPropertyDirection:
            return cssValuePool.createValue(style.direction());
        case CSSPropertyDisplay:
            return cssValuePool.createValue(style.display());
        case CSSPropertyEmptyCells:
            return cssValuePool.createValue(style.emptyCells());
        case CSSPropertyAlignContent:
            return valueForContentPositionAndDistributionWithOverflowAlignment(style.alignContent());
        case CSSPropertyAlignItems:
            return valueForItemPositionWithOverflowAlignment(style.alignItems());
        case CSSPropertyAlignSelf:
            return valueForItemPositionWithOverflowAlignment(style.alignSelf());
        case CSSPropertyFlex:
            return getCSSPropertyValuesForShorthandProperties(flexShorthand());
        case CSSPropertyFlexBasis:
            return cssValuePool.createValue(style.flexBasis(), style);
        case CSSPropertyFlexDirection:
            return cssValuePool.createValue(style.flexDirection());
        case CSSPropertyFlexFlow:
            return getCSSPropertyValuesForShorthandProperties(flexFlowShorthand());
        case CSSPropertyFlexGrow:
            return cssValuePool.createValue(style.flexGrow());
        case CSSPropertyFlexShrink:
            return cssValuePool.createValue(style.flexShrink());
        case CSSPropertyFlexWrap:
            return cssValuePool.createValue(style.flexWrap());
        case CSSPropertyJustifyContent:
            return valueForContentPositionAndDistributionWithOverflowAlignment(style.justifyContent());
        case CSSPropertyJustifyItems:
            return valueForItemPositionWithOverflowAlignment(style.justifyItems());
        case CSSPropertyJustifySelf:
            return valueForItemPositionWithOverflowAlignment(style.justifySelf());
        case CSSPropertyPlaceContent:
            return getCSSPropertyValuesForShorthandProperties(placeContentShorthand());
        case CSSPropertyPlaceItems:
            return getCSSPropertyValuesForShorthandProperties(placeItemsShorthand());
        case CSSPropertyPlaceSelf:
            return getCSSPropertyValuesForShorthandProperties(placeSelfShorthand());
        case CSSPropertyOrder:
            return cssValuePool.createValue(style.order(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyFloat:
            if (style.display() != DisplayType::None && style.hasOutOfFlowPosition())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return cssValuePool.createValue(style.floating());
        case CSSPropertyFont: {
            auto computedFont = fontShorthandValueForSelectionProperties(style.fontDescription());
            computedFont->size = fontSizeFromStyle(style);
            computedFont->lineHeight = lineHeightFromStyle(style);
            computedFont->family = fontFamilyListFromStyle(style);
            return WTFMove(computedFont);
        }
        case CSSPropertyFontFamily:
            return fontFamilyFromStyle(style);
        case CSSPropertyFontSize:
            return fontSizeFromStyle(style);
        case CSSPropertyFontStyle:
            return fontStyleFromStyle(style);
        case CSSPropertyFontStretch:
            return fontStretchFromStyle(style);
        case CSSPropertyFontVariant:
            return fontVariantFromStyle(style);
        case CSSPropertyFontWeight:
            return fontWeightFromStyle(style);
        case CSSPropertyFontSynthesis:
            return fontSynthesisFromStyle(style);
        case CSSPropertyFontFeatureSettings: {
            const FontFeatureSettings& featureSettings = style.fontDescription().featureSettings();
            if (!featureSettings.size())
                return cssValuePool.createIdentifierValue(CSSValueNormal);
            auto list = CSSValueList::createCommaSeparated();
            for (auto& feature : featureSettings)
                list->append(CSSFontFeatureValue::create(FontTag(feature.tag()), feature.value()));
            return WTFMove(list);
        }
#if ENABLE(VARIATION_FONTS)
        case CSSPropertyFontVariationSettings: {
            const FontVariationSettings& variationSettings = style.fontDescription().variationSettings();
            if (variationSettings.isEmpty())
                return cssValuePool.createIdentifierValue(CSSValueNormal);
            auto list = CSSValueList::createCommaSeparated();
            for (auto& feature : variationSettings)
                list->append(CSSFontVariationValue::create(feature.tag(), feature.value()));
            return WTFMove(list);
        }
        case CSSPropertyFontOpticalSizing:
            return cssValuePool.createValue(style.fontDescription().opticalSizing());
#endif
        case CSSPropertyGridAutoFlow: {
            auto list = CSSValueList::createSpaceSeparated();
            ASSERT(style.isGridAutoFlowDirectionRow() || style.isGridAutoFlowDirectionColumn());
            if (style.isGridAutoFlowDirectionRow())
                list->append(cssValuePool.createIdentifierValue(CSSValueRow));
            else
                list->append(cssValuePool.createIdentifierValue(CSSValueColumn));

            if (style.isGridAutoFlowAlgorithmDense())
                list->append(cssValuePool.createIdentifierValue(CSSValueDense));

            return WTFMove(list);
        }

        // Specs mention that getComputedStyle() should return the used value of the property instead of the computed
        // one for grid-template-{rows|columns} but not for the grid-auto-{rows|columns} as things like
        // grid-auto-columns: 2fr; cannot be resolved to a value in pixels as the '2fr' means very different things
        // depending on the size of the explicit grid or the number of implicit tracks added to the grid. See
        // http://lists.w3.org/Archives/Public/www-style/2013Nov/0014.html
        case CSSPropertyGridAutoColumns:
            return valueForGridTrackSizeList(ForColumns, style);
        case CSSPropertyGridAutoRows:
            return valueForGridTrackSizeList(ForRows, style);

        case CSSPropertyGridTemplateColumns:
            return valueForGridTrackList(ForColumns, renderer, style);
        case CSSPropertyGridTemplateRows:
            return valueForGridTrackList(ForRows, renderer, style);

        case CSSPropertyGridColumnStart:
            return valueForGridPosition(style.gridItemColumnStart());
        case CSSPropertyGridColumnEnd:
            return valueForGridPosition(style.gridItemColumnEnd());
        case CSSPropertyGridRowStart:
            return valueForGridPosition(style.gridItemRowStart());
        case CSSPropertyGridRowEnd:
            return valueForGridPosition(style.gridItemRowEnd());
        case CSSPropertyGridArea:
            return getCSSPropertyValuesForGridShorthand(gridAreaShorthand());
        case CSSPropertyGridTemplate:
            return getCSSPropertyValuesForGridShorthand(gridTemplateShorthand());
        case CSSPropertyGrid:
            return getCSSPropertyValuesForGridShorthand(gridShorthand());
        case CSSPropertyGridColumn:
            return getCSSPropertyValuesForGridShorthand(gridColumnShorthand());
        case CSSPropertyGridRow:
            return getCSSPropertyValuesForGridShorthand(gridRowShorthand());
        case CSSPropertyGridTemplateAreas:
            if (!style.namedGridAreaRowCount()) {
                ASSERT(!style.namedGridAreaColumnCount());
                return cssValuePool.createIdentifierValue(CSSValueNone);
            }
            return CSSGridTemplateAreasValue::create(style.namedGridArea(), style.namedGridAreaRowCount(), style.namedGridAreaColumnCount());
        case CSSPropertyGap:
            return getCSSPropertyValuesForShorthandProperties(gapShorthand());
        case CSSPropertyHeight:
            if (renderer && !renderer->isRenderSVGModelObject()) {
                // According to http://www.w3.org/TR/CSS2/visudet.html#the-height-property,
                // the "height" property does not apply for non-replaced inline elements.
                if (isNonReplacedInline(*renderer))
                    return cssValuePool.createIdentifierValue(CSSValueAuto);
                return zoomAdjustedPixelValue(sizingBox(*renderer).height(), style);
            }
            return zoomAdjustedPixelValueForLength(style.height(), style);
        case CSSPropertyWebkitHyphens:
            return cssValuePool.createValue(style.hyphens());
        case CSSPropertyWebkitHyphenateCharacter:
            if (style.hyphenationString().isNull())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.hyphenationString(), CSSPrimitiveValue::CSS_STRING);
        case CSSPropertyWebkitHyphenateLimitAfter:
            if (style.hyphenationLimitAfter() < 0)
                return CSSPrimitiveValue::createIdentifier(CSSValueAuto);
            return CSSPrimitiveValue::create(style.hyphenationLimitAfter(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitHyphenateLimitBefore:
            if (style.hyphenationLimitBefore() < 0)
                return CSSPrimitiveValue::createIdentifier(CSSValueAuto);
            return CSSPrimitiveValue::create(style.hyphenationLimitBefore(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitHyphenateLimitLines:
            if (style.hyphenationLimitLines() < 0)
                return CSSPrimitiveValue::createIdentifier(CSSValueNoLimit);
            return CSSPrimitiveValue::create(style.hyphenationLimitLines(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitBorderFit:
            if (style.borderFit() == BorderFit::Border)
                return cssValuePool.createIdentifierValue(CSSValueBorder);
            return cssValuePool.createIdentifierValue(CSSValueLines);
#if ENABLE(CSS_IMAGE_ORIENTATION)
        case CSSPropertyImageOrientation:
            return cssValuePool.createValue(style.imageOrientation());
#endif
        case CSSPropertyImageRendering:
            return CSSPrimitiveValue::create(style.imageRendering());
#if ENABLE(CSS_IMAGE_RESOLUTION)
        case CSSPropertyImageResolution:
            return cssValuePool.createValue(style.imageResolution(), CSSPrimitiveValue::CSS_DPPX);
#endif
        case CSSPropertyLeft:
            return positionOffsetValue(style, CSSPropertyLeft, renderer);
        case CSSPropertyLetterSpacing:
            if (!style.letterSpacing())
                return cssValuePool.createIdentifierValue(CSSValueNormal);
            return zoomAdjustedPixelValue(style.letterSpacing(), style);
        case CSSPropertyWebkitLineClamp:
            if (style.lineClamp().isNone())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return cssValuePool.createValue(style.lineClamp().value(), style.lineClamp().isPercentage() ? CSSPrimitiveValue::CSS_PERCENTAGE : CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyLineHeight:
            return lineHeightFromStyle(style);
        case CSSPropertyListStyleImage:
            if (style.listStyleImage())
                return style.listStyleImage()->cssValue();
            return cssValuePool.createIdentifierValue(CSSValueNone);
        case CSSPropertyListStylePosition:
            return cssValuePool.createValue(style.listStylePosition());
        case CSSPropertyListStyleType:
            return cssValuePool.createValue(style.listStyleType());
        case CSSPropertyWebkitLocale:
            if (style.locale().isNull())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.locale(), CSSPrimitiveValue::CSS_STRING);
        case CSSPropertyMarginTop:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::marginTop, &RenderBoxModelObject::marginTop>(style, renderer);
        case CSSPropertyMarginRight: {
            Length marginRight = style.marginRight();
            if (marginRight.isFixed() || !is<RenderBox>(renderer))
                return zoomAdjustedPixelValueForLength(marginRight, style);
            float value;
            if (marginRight.isPercentOrCalculated()) {
                // RenderBox gives a marginRight() that is the distance between the right-edge of the child box
                // and the right-edge of the containing box, when display == DisplayType::Block. Let's calculate the absolute
                // value of the specified margin-right % instead of relying on RenderBox's marginRight() value.
                value = minimumValueForLength(marginRight, downcast<RenderBox>(*renderer).containingBlockLogicalWidthForContent());
            } else
                value = downcast<RenderBox>(*renderer).marginRight();
            return zoomAdjustedPixelValue(value, style);
        }
        case CSSPropertyMarginBottom:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::marginBottom, &RenderBoxModelObject::marginBottom>(style, renderer);
        case CSSPropertyMarginLeft:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::marginLeft, &RenderBoxModelObject::marginLeft>(style, renderer);
        case CSSPropertyWebkitMarqueeDirection:
            return cssValuePool.createValue(style.marqueeDirection());
        case CSSPropertyWebkitMarqueeIncrement:
            return cssValuePool.createValue(style.marqueeIncrement());
        case CSSPropertyWebkitMarqueeRepetition:
            if (style.marqueeLoopCount() < 0)
                return cssValuePool.createIdentifierValue(CSSValueInfinite);
            return cssValuePool.createValue(style.marqueeLoopCount(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWebkitMarqueeStyle:
            return cssValuePool.createValue(style.marqueeBehavior());
        case CSSPropertyWebkitUserModify:
            return cssValuePool.createValue(style.userModify());
        case CSSPropertyMaxHeight: {
            const Length& maxHeight = style.maxHeight();
            if (maxHeight.isUndefined())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return zoomAdjustedPixelValueForLength(maxHeight, style);
        }
        case CSSPropertyMaxWidth: {
            const Length& maxWidth = style.maxWidth();
            if (maxWidth.isUndefined())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return zoomAdjustedPixelValueForLength(maxWidth, style);
        }
        case CSSPropertyMinHeight:
            if (style.minHeight().isAuto()) {
                auto* styledElement = this->styledElement();
                if (styledElement && isFlexOrGrid(styledElement->parentNode()))
                    return cssValuePool.createIdentifierValue(CSSValueAuto);
                return zoomAdjustedPixelValue(0, style);
            }
            return zoomAdjustedPixelValueForLength(style.minHeight(), style);
        case CSSPropertyMinWidth:
            if (style.minWidth().isAuto()) {
                auto* styledElement = this->styledElement();
                if (styledElement && isFlexOrGrid(styledElement->parentNode()))
                    return cssValuePool.createIdentifierValue(CSSValueAuto);
                return zoomAdjustedPixelValue(0, style);
            }
            return zoomAdjustedPixelValueForLength(style.minWidth(), style);
        case CSSPropertyObjectFit:
            return cssValuePool.createValue(style.objectFit());
        case CSSPropertyObjectPosition: {
            auto list = CSSValueList::createSpaceSeparated();
            list->append(zoomAdjustedPixelValueForLength(style.objectPosition().x(), style));
            list->append(zoomAdjustedPixelValueForLength(style.objectPosition().y(), style));
            return WTFMove(list);
        }
        case CSSPropertyOpacity:
            return cssValuePool.createValue(style.opacity(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyOrphans:
            if (style.hasAutoOrphans())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.orphans(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyOutlineColor:
            return m_allowVisitedStyle ? cssValuePool.createColorValue(style.visitedDependentColor(CSSPropertyOutlineColor)) : currentColorOrValidColor(&style, style.outlineColor());
        case CSSPropertyOutlineOffset:
            return zoomAdjustedPixelValue(style.outlineOffset(), style);
        case CSSPropertyOutlineStyle:
            if (style.outlineStyleIsAuto() == OutlineIsAuto::On)
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.outlineStyle());
        case CSSPropertyOutlineWidth:
            return zoomAdjustedPixelValue(style.outlineWidth(), style);
        case CSSPropertyOverflow:
            return cssValuePool.createValue(std::max(style.overflowX(), style.overflowY()));
        case CSSPropertyOverflowWrap:
            return cssValuePool.createValue(style.overflowWrap());
        case CSSPropertyOverflowX:
            return cssValuePool.createValue(style.overflowX());
        case CSSPropertyOverflowY:
            return cssValuePool.createValue(style.overflowY());
        case CSSPropertyPaddingTop:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::paddingTop, &RenderBoxModelObject::computedCSSPaddingTop>(style, renderer);
        case CSSPropertyPaddingRight:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::paddingRight, &RenderBoxModelObject::computedCSSPaddingRight>(style, renderer);
        case CSSPropertyPaddingBottom:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::paddingBottom, &RenderBoxModelObject::computedCSSPaddingBottom>(style, renderer);
        case CSSPropertyPaddingLeft:
            return zoomAdjustedPaddingOrMarginPixelValue<&RenderStyle::paddingLeft, &RenderBoxModelObject::computedCSSPaddingLeft>(style, renderer);
        case CSSPropertyPageBreakAfter:
            return cssValuePool.createValue(convertToPageBreak(style.breakAfter()));
        case CSSPropertyPageBreakBefore:
            return cssValuePool.createValue(convertToPageBreak(style.breakBefore()));
        case CSSPropertyPageBreakInside:
            return cssValuePool.createValue(convertToPageBreak(style.breakInside()));
        case CSSPropertyBreakAfter:
            return cssValuePool.createValue(style.breakAfter());
        case CSSPropertyBreakBefore:
            return cssValuePool.createValue(style.breakBefore());
        case CSSPropertyBreakInside:
            return cssValuePool.createValue(style.breakInside());
        case CSSPropertyHangingPunctuation:
            return hangingPunctuationToCSSValue(style.hangingPunctuation());
        case CSSPropertyPosition:
            return cssValuePool.createValue(style.position());
        case CSSPropertyRight:
            return positionOffsetValue(style, CSSPropertyRight, renderer);
        case CSSPropertyWebkitRubyPosition:
            return cssValuePool.createValue(style.rubyPosition());
        case CSSPropertyTableLayout:
            return cssValuePool.createValue(style.tableLayout());
        case CSSPropertyTextAlign:
            return cssValuePool.createValue(style.textAlign());
        case CSSPropertyTextDecoration:
            return renderTextDecorationFlagsToCSSValue(style.textDecoration());
#if ENABLE(CSS3_TEXT)
        case CSSPropertyWebkitTextAlignLast:
            return cssValuePool.createValue(style.textAlignLast());
        case CSSPropertyWebkitTextJustify:
            return cssValuePool.createValue(style.textJustify());
#endif // CSS3_TEXT
        case CSSPropertyWebkitTextDecoration:
            return getCSSPropertyValuesForShorthandProperties(webkitTextDecorationShorthand());
        case CSSPropertyWebkitTextDecorationLine:
            return renderTextDecorationFlagsToCSSValue(style.textDecoration());
        case CSSPropertyWebkitTextDecorationStyle:
            return renderTextDecorationStyleFlagsToCSSValue(style.textDecorationStyle());
        case CSSPropertyWebkitTextDecorationColor:
            return currentColorOrValidColor(&style, style.textDecorationColor());
        case CSSPropertyWebkitTextDecorationSkip:
            return renderTextDecorationSkipFlagsToCSSValue(style.textDecorationSkip());
        case CSSPropertyWebkitTextUnderlinePosition:
            return cssValuePool.createValue(style.textUnderlinePosition());
        case CSSPropertyWebkitTextDecorationsInEffect:
            return renderTextDecorationFlagsToCSSValue(style.textDecorationsInEffect());
        case CSSPropertyWebkitTextFillColor:
            return currentColorOrValidColor(&style, style.textFillColor());
        case CSSPropertyWebkitTextEmphasisColor:
            return currentColorOrValidColor(&style, style.textEmphasisColor());
        case CSSPropertyWebkitTextEmphasisPosition:
            return renderEmphasisPositionFlagsToCSSValue(style.textEmphasisPosition());
        case CSSPropertyWebkitTextEmphasisStyle:
            switch (style.textEmphasisMark()) {
            case TextEmphasisMark::None:
                return cssValuePool.createIdentifierValue(CSSValueNone);
            case TextEmphasisMark::Custom:
                return cssValuePool.createValue(style.textEmphasisCustomMark(), CSSPrimitiveValue::CSS_STRING);
            case TextEmphasisMark::Auto:
                ASSERT_NOT_REACHED();
#if ASSERT_DISABLED
                FALLTHROUGH;
#endif
            case TextEmphasisMark::Dot:
            case TextEmphasisMark::Circle:
            case TextEmphasisMark::DoubleCircle:
            case TextEmphasisMark::Triangle:
            case TextEmphasisMark::Sesame:
                auto list = CSSValueList::createSpaceSeparated();
                list->append(cssValuePool.createValue(style.textEmphasisFill()));
                list->append(cssValuePool.createValue(style.textEmphasisMark()));
                return WTFMove(list);
            }
            RELEASE_ASSERT_NOT_REACHED();
        case CSSPropertyTextIndent: {
            // If CSS3_TEXT is disabled or text-indent has only one value(<length> | <percentage>),
            // getPropertyCSSValue() returns CSSValue.
            auto textIndent = zoomAdjustedPixelValueForLength(style.textIndent(), style);
#if ENABLE(CSS3_TEXT)
            // If CSS3_TEXT is enabled and text-indent has -webkit-each-line or -webkit-hanging,
            // getPropertyCSSValue() returns CSSValueList.
            if (style.textIndentLine() == TextIndentLine::EachLine || style.textIndentType() == TextIndentType::Hanging) {
                auto list = CSSValueList::createSpaceSeparated();
                list->append(WTFMove(textIndent));
                if (style.textIndentLine() == TextIndentLine::EachLine)
                    list->append(cssValuePool.createIdentifierValue(CSSValueWebkitEachLine));
                if (style.textIndentType() == TextIndentType::Hanging)
                    list->append(cssValuePool.createIdentifierValue(CSSValueWebkitHanging));
                return WTFMove(list);
            }
#endif
            return WTFMove(textIndent);
        }
        case CSSPropertyTextShadow:
            return valueForShadow(style.textShadow(), propertyID, style);
        case CSSPropertyTextRendering:
            return cssValuePool.createValue(style.fontDescription().textRenderingMode());
        case CSSPropertyTextOverflow:
            if (style.textOverflow() == TextOverflow::Ellipsis)
                return cssValuePool.createIdentifierValue(CSSValueEllipsis);
            return cssValuePool.createIdentifierValue(CSSValueClip);
        case CSSPropertyWebkitTextSecurity:
            return cssValuePool.createValue(style.textSecurity());
#if ENABLE(TEXT_AUTOSIZING)
        case CSSPropertyWebkitTextSizeAdjust:
            if (style.textSizeAdjust().isAuto())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            if (style.textSizeAdjust().isNone())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return CSSPrimitiveValue::create(style.textSizeAdjust().percentage(), CSSPrimitiveValue::CSS_PERCENTAGE);
#endif
        case CSSPropertyWebkitTextStrokeColor:
            return currentColorOrValidColor(&style, style.textStrokeColor());
        case CSSPropertyWebkitTextStrokeWidth:
            return zoomAdjustedPixelValue(style.textStrokeWidth(), style);
        case CSSPropertyTextTransform:
            return cssValuePool.createValue(style.textTransform());
        case CSSPropertyTop:
            return positionOffsetValue(style, CSSPropertyTop, renderer);
        case CSSPropertyUnicodeBidi:
            return cssValuePool.createValue(style.unicodeBidi());
        case CSSPropertyVerticalAlign:
            switch (style.verticalAlign()) {
            case VerticalAlign::Baseline:
                return cssValuePool.createIdentifierValue(CSSValueBaseline);
            case VerticalAlign::Middle:
                return cssValuePool.createIdentifierValue(CSSValueMiddle);
            case VerticalAlign::Sub:
                return cssValuePool.createIdentifierValue(CSSValueSub);
            case VerticalAlign::Super:
                return cssValuePool.createIdentifierValue(CSSValueSuper);
            case VerticalAlign::TextTop:
                return cssValuePool.createIdentifierValue(CSSValueTextTop);
            case VerticalAlign::TextBottom:
                return cssValuePool.createIdentifierValue(CSSValueTextBottom);
            case VerticalAlign::Top:
                return cssValuePool.createIdentifierValue(CSSValueTop);
            case VerticalAlign::Bottom:
                return cssValuePool.createIdentifierValue(CSSValueBottom);
            case VerticalAlign::BaselineMiddle:
                return cssValuePool.createIdentifierValue(CSSValueWebkitBaselineMiddle);
            case VerticalAlign::Length:
                return cssValuePool.createValue(style.verticalAlignLength());
            }
            ASSERT_NOT_REACHED();
            return nullptr;
        case CSSPropertyVisibility:
            return cssValuePool.createValue(style.visibility());
        case CSSPropertyWhiteSpace:
            return cssValuePool.createValue(style.whiteSpace());
        case CSSPropertyWidows:
            if (style.hasAutoWidows())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.widows(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyWidth:
            if (renderer && !renderer->isRenderSVGModelObject()) {
                // According to http://www.w3.org/TR/CSS2/visudet.html#the-width-property,
                // the "width" property does not apply for non-replaced inline elements.
                if (isNonReplacedInline(*renderer))
                    return cssValuePool.createIdentifierValue(CSSValueAuto);
                return zoomAdjustedPixelValue(sizingBox(*renderer).width(), style);
            }
            return zoomAdjustedPixelValueForLength(style.width(), style);
        case CSSPropertyWillChange:
            return willChangePropertyValue(style.willChange());
        case CSSPropertyWordBreak:
            return cssValuePool.createValue(style.wordBreak());
        case CSSPropertyWordSpacing:
            return zoomAdjustedPixelValue(style.fontCascade().wordSpacing(), style);
        case CSSPropertyWordWrap:
            return cssValuePool.createValue(style.overflowWrap());
        case CSSPropertyLineBreak:
            return cssValuePool.createValue(style.lineBreak());
        case CSSPropertyWebkitNbspMode:
            return cssValuePool.createValue(style.nbspMode());
        case CSSPropertyResize:
            return cssValuePool.createValue(style.resize());
        case CSSPropertyWebkitFontKerning:
            return cssValuePool.createValue(style.fontDescription().kerning());
        case CSSPropertyWebkitFontSmoothing:
            return cssValuePool.createValue(style.fontDescription().fontSmoothing());
        case CSSPropertyFontVariantLigatures:
            return fontVariantLigaturesPropertyValue(style.fontDescription().variantCommonLigatures(), style.fontDescription().variantDiscretionaryLigatures(), style.fontDescription().variantHistoricalLigatures(), style.fontDescription().variantContextualAlternates());
        case CSSPropertyFontVariantPosition:
            return fontVariantPositionPropertyValue(style.fontDescription().variantPosition());
        case CSSPropertyFontVariantCaps:
            return fontVariantCapsPropertyValue(style.fontDescription().variantCaps());
        case CSSPropertyFontVariantNumeric:
            return fontVariantNumericPropertyValue(style.fontDescription().variantNumericFigure(), style.fontDescription().variantNumericSpacing(), style.fontDescription().variantNumericFraction(), style.fontDescription().variantNumericOrdinal(), style.fontDescription().variantNumericSlashedZero());
        case CSSPropertyFontVariantAlternates:
            return fontVariantAlternatesPropertyValue(style.fontDescription().variantAlternates());
        case CSSPropertyFontVariantEastAsian:
            return fontVariantEastAsianPropertyValue(style.fontDescription().variantEastAsianVariant(), style.fontDescription().variantEastAsianWidth(), style.fontDescription().variantEastAsianRuby());
        case CSSPropertyZIndex:
            if (style.hasAutoZIndex())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createValue(style.zIndex(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyZoom:
            return cssValuePool.createValue(style.zoom(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyBoxSizing:
            if (style.boxSizing() == BoxSizing::ContentBox)
                return cssValuePool.createIdentifierValue(CSSValueContentBox);
            return cssValuePool.createIdentifierValue(CSSValueBorderBox);
#if ENABLE(DASHBOARD_SUPPORT)
        case CSSPropertyWebkitDashboardRegion:
        {
            const Vector<StyleDashboardRegion>& regions = style.dashboardRegions();
            unsigned count = regions.size();
            if (count == 1 && regions[0].type == StyleDashboardRegion::None)
                return cssValuePool.createIdentifierValue(CSSValueNone);

            RefPtr<DashboardRegion> firstRegion;
            DashboardRegion* previousRegion = nullptr;
            for (unsigned i = 0; i < count; i++) {
                auto region = DashboardRegion::create();
                StyleDashboardRegion styleRegion = regions[i];

                region->m_label = styleRegion.label;
                LengthBox offset = styleRegion.offset;
                region->setTop(zoomAdjustedPixelValue(offset.top().value(), style));
                region->setRight(zoomAdjustedPixelValue(offset.right().value(), style));
                region->setBottom(zoomAdjustedPixelValue(offset.bottom().value(), style));
                region->setLeft(zoomAdjustedPixelValue(offset.left().value(), style));
                region->m_isRectangle = (styleRegion.type == StyleDashboardRegion::Rectangle);
                region->m_isCircle = (styleRegion.type == StyleDashboardRegion::Circle);

                if (previousRegion)
                    previousRegion->m_next = region.copyRef();
                else
                    firstRegion = region.copyRef();
                previousRegion = region.ptr();
            }
            return cssValuePool.createValue(WTFMove(firstRegion));
        }
#endif
        case CSSPropertyAnimationDelay:
            return delayValue(style.animations());
        case CSSPropertyAnimationDirection: {
            auto list = CSSValueList::createCommaSeparated();
            const AnimationList* t = style.animations();
            if (t) {
                for (size_t i = 0; i < t->size(); ++i) {
                    switch (t->animation(i).direction()) {
                    case Animation::AnimationDirectionNormal:
                        list->append(cssValuePool.createIdentifierValue(CSSValueNormal));
                        break;
                    case Animation::AnimationDirectionAlternate:
                        list->append(cssValuePool.createIdentifierValue(CSSValueAlternate));
                        break;
                    case Animation::AnimationDirectionReverse:
                        list->append(cssValuePool.createIdentifierValue(CSSValueReverse));
                        break;
                    case Animation::AnimationDirectionAlternateReverse:
                        list->append(cssValuePool.createIdentifierValue(CSSValueAlternateReverse));
                        break;
                    }
                }
            } else
                list->append(cssValuePool.createIdentifierValue(CSSValueNormal));
            return WTFMove(list);
        }
        case CSSPropertyAnimationDuration:
            return durationValue(style.animations());
        case CSSPropertyAnimationFillMode: {
            auto list = CSSValueList::createCommaSeparated();
            const AnimationList* t = style.animations();
            if (t) {
                for (size_t i = 0; i < t->size(); ++i) {
                    switch (t->animation(i).fillMode()) {
                    case AnimationFillMode::None:
                        list->append(cssValuePool.createIdentifierValue(CSSValueNone));
                        break;
                    case AnimationFillMode::Forwards:
                        list->append(cssValuePool.createIdentifierValue(CSSValueForwards));
                        break;
                    case AnimationFillMode::Backwards:
                        list->append(cssValuePool.createIdentifierValue(CSSValueBackwards));
                        break;
                    case AnimationFillMode::Both:
                        list->append(cssValuePool.createIdentifierValue(CSSValueBoth));
                        break;
                    }
                }
            } else
                list->append(cssValuePool.createIdentifierValue(CSSValueNone));
            return WTFMove(list);
        }
        case CSSPropertyAnimationIterationCount: {
            auto list = CSSValueList::createCommaSeparated();
            const AnimationList* t = style.animations();
            if (t) {
                for (size_t i = 0; i < t->size(); ++i) {
                    double iterationCount = t->animation(i).iterationCount();
                    if (iterationCount == Animation::IterationCountInfinite)
                        list->append(cssValuePool.createIdentifierValue(CSSValueInfinite));
                    else
                        list->append(cssValuePool.createValue(iterationCount, CSSPrimitiveValue::CSS_NUMBER));
                }
            } else
                list->append(cssValuePool.createValue(Animation::initialIterationCount(), CSSPrimitiveValue::CSS_NUMBER));
            return WTFMove(list);
        }
        case CSSPropertyAnimationName: {
            auto list = CSSValueList::createCommaSeparated();
            const AnimationList* t = style.animations();
            if (t) {
                for (size_t i = 0; i < t->size(); ++i)
                    list->append(cssValuePool.createValue(t->animation(i).name(), CSSPrimitiveValue::CSS_STRING));
            } else
                list->append(cssValuePool.createIdentifierValue(CSSValueNone));
            return WTFMove(list);
        }
        case CSSPropertyAnimationPlayState: {
            auto list = CSSValueList::createCommaSeparated();
            const AnimationList* t = style.animations();
            if (t) {
                for (size_t i = 0; i < t->size(); ++i) {
                    switch (t->animation(i).playState()) {
                    case AnimationPlayState::Playing:
                        list->append(cssValuePool.createIdentifierValue(CSSValueRunning));
                        break;
                    case AnimationPlayState::Paused:
                        list->append(cssValuePool.createIdentifierValue(CSSValuePaused));
                        break;
                    }
                }
            } else
                list->append(cssValuePool.createIdentifierValue(CSSValueRunning));
            return WTFMove(list);
        }
        case CSSPropertyAnimationTimingFunction:
            return timingFunctionValue(style.animations());
#if ENABLE(CSS_ANIMATIONS_LEVEL_2)
        case CSSPropertyWebkitAnimationTrigger:
            return animationTriggerValue(style.animations(), style);
#endif
        case CSSPropertyWebkitAppearance:
            return cssValuePool.createValue(style.appearance());
        case CSSPropertyWebkitAspectRatio:
            switch (style.aspectRatioType()) {
            case AspectRatioType::Auto:
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            case AspectRatioType::FromDimensions:
                return cssValuePool.createIdentifierValue(CSSValueFromDimensions);
            case AspectRatioType::FromIntrinsic:
                return cssValuePool.createIdentifierValue(CSSValueFromIntrinsic);
            case AspectRatioType::Specified:
                return CSSAspectRatioValue::create(style.aspectRatioNumerator(), style.aspectRatioDenominator());
            }
            ASSERT_NOT_REACHED();
            return nullptr;
        case CSSPropertyWebkitBackfaceVisibility:
            return cssValuePool.createIdentifierValue((style.backfaceVisibility() == BackfaceVisibility::Hidden) ? CSSValueHidden : CSSValueVisible);
        case CSSPropertyWebkitBorderImage:
            return valueForNinePieceImage(style.borderImage());
        case CSSPropertyBorderImageOutset:
            return valueForNinePieceImageQuad(style.borderImage().outset());
        case CSSPropertyBorderImageRepeat:
            return valueForNinePieceImageRepeat(style.borderImage());
        case CSSPropertyBorderImageSlice:
            return valueForNinePieceImageSlice(style.borderImage());
        case CSSPropertyBorderImageWidth:
            return valueForNinePieceImageQuad(style.borderImage().borderSlices());
        case CSSPropertyWebkitMaskBoxImage:
            return valueForNinePieceImage(style.maskBoxImage());
        case CSSPropertyWebkitMaskBoxImageOutset:
            return valueForNinePieceImageQuad(style.maskBoxImage().outset());
        case CSSPropertyWebkitMaskBoxImageRepeat:
            return valueForNinePieceImageRepeat(style.maskBoxImage());
        case CSSPropertyWebkitMaskBoxImageSlice:
            return valueForNinePieceImageSlice(style.maskBoxImage());
        case CSSPropertyWebkitMaskBoxImageWidth:
            return valueForNinePieceImageQuad(style.maskBoxImage().borderSlices());
        case CSSPropertyWebkitMaskBoxImageSource:
            if (style.maskBoxImageSource())
                return style.maskBoxImageSource()->cssValue();
            return cssValuePool.createIdentifierValue(CSSValueNone);
        case CSSPropertyWebkitFontSizeDelta:
            // Not a real style property -- used by the editing engine -- so has no computed value.
            break;
        case CSSPropertyWebkitInitialLetter: {
            auto drop = !style.initialLetterDrop() ? cssValuePool.createIdentifierValue(CSSValueNormal) : cssValuePool.createValue(style.initialLetterDrop(), CSSPrimitiveValue::CSS_NUMBER);
            auto size = !style.initialLetterHeight() ? cssValuePool.createIdentifierValue(CSSValueNormal) : cssValuePool.createValue(style.initialLetterHeight(), CSSPrimitiveValue::CSS_NUMBER);
            return cssValuePool.createValue(Pair::create(WTFMove(drop), WTFMove(size)));
        }
        case CSSPropertyWebkitMarginBottomCollapse:
        case CSSPropertyWebkitMarginAfterCollapse:
            return cssValuePool.createValue(style.marginAfterCollapse());
        case CSSPropertyWebkitMarginTopCollapse:
        case CSSPropertyWebkitMarginBeforeCollapse:
            return cssValuePool.createValue(style.marginBeforeCollapse());
#if ENABLE(ACCELERATED_OVERFLOW_SCROLLING)
        case CSSPropertyWebkitOverflowScrolling:
            if (!style.useTouchOverflowScrolling())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            return cssValuePool.createIdentifierValue(CSSValueTouch);
#endif
        case CSSPropertyPerspective:
            if (!style.hasPerspective())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return zoomAdjustedPixelValue(style.perspective(), style);
        case CSSPropertyPerspectiveOrigin: {
            auto list = CSSValueList::createSpaceSeparated();
            if (renderer) {
                LayoutRect box;
                if (is<RenderBox>(*renderer))
                    box = downcast<RenderBox>(*renderer).borderBoxRect();

                list->append(zoomAdjustedPixelValue(minimumValueForLength(style.perspectiveOriginX(), box.width()), style));
                list->append(zoomAdjustedPixelValue(minimumValueForLength(style.perspectiveOriginY(), box.height()), style));
            } else {
                list->append(zoomAdjustedPixelValueForLength(style.perspectiveOriginX(), style));
                list->append(zoomAdjustedPixelValueForLength(style.perspectiveOriginY(), style));
            }
            return WTFMove(list);
        }
        case CSSPropertyWebkitRtlOrdering:
            return cssValuePool.createIdentifierValue(style.rtlOrdering() == Order::Visual ? CSSValueVisual : CSSValueLogical);
#if ENABLE(TOUCH_EVENTS)
        case CSSPropertyWebkitTapHighlightColor:
            return currentColorOrValidColor(&style, style.tapHighlightColor());
        case CSSPropertyTouchAction:
            return cssValuePool.createValue(style.touchAction());
#endif
#if PLATFORM(IOS)
        case CSSPropertyWebkitTouchCallout:
            return cssValuePool.createIdentifierValue(style.touchCalloutEnabled() ? CSSValueDefault : CSSValueNone);
#endif
        case CSSPropertyWebkitUserDrag:
            return cssValuePool.createValue(style.userDrag());
        case CSSPropertyWebkitUserSelect:
            return cssValuePool.createValue(style.userSelect());
        case CSSPropertyBorderBottomLeftRadius:
            return borderRadiusCornerValue(style.borderBottomLeftRadius(), style);
        case CSSPropertyBorderBottomRightRadius:
            return borderRadiusCornerValue(style.borderBottomRightRadius(), style);
        case CSSPropertyBorderTopLeftRadius:
            return borderRadiusCornerValue(style.borderTopLeftRadius(), style);
        case CSSPropertyBorderTopRightRadius:
            return borderRadiusCornerValue(style.borderTopRightRadius(), style);
        case CSSPropertyClip: {
            if (!style.hasClip())
                return cssValuePool.createIdentifierValue(CSSValueAuto);
            auto rect = Rect::create();
            rect->setTop(autoOrZoomAdjustedValue(style.clip().top(), style));
            rect->setRight(autoOrZoomAdjustedValue(style.clip().right(), style));
            rect->setBottom(autoOrZoomAdjustedValue(style.clip().bottom(), style));
            rect->setLeft(autoOrZoomAdjustedValue(style.clip().left(), style));
            return cssValuePool.createValue(WTFMove(rect));
        }
        case CSSPropertySpeakAs:
            return speakAsToCSSValue(style.speakAs());
        case CSSPropertyTransform:
            return computedTransform(renderer, style);
        case CSSPropertyTransformBox:
            return CSSPrimitiveValue::create(style.transformBox());
        case CSSPropertyTransformOrigin: {
            auto list = CSSValueList::createSpaceSeparated();
            if (renderer) {
                LayoutRect box;
                if (is<RenderBox>(*renderer))
                    box = downcast<RenderBox>(*renderer).borderBoxRect();

                list->append(zoomAdjustedPixelValue(minimumValueForLength(style.transformOriginX(), box.width()), style));
                list->append(zoomAdjustedPixelValue(minimumValueForLength(style.transformOriginY(), box.height()), style));
                if (style.transformOriginZ())
                    list->append(zoomAdjustedPixelValue(style.transformOriginZ(), style));
            } else {
                list->append(zoomAdjustedPixelValueForLength(style.transformOriginX(), style));
                list->append(zoomAdjustedPixelValueForLength(style.transformOriginY(), style));
                if (style.transformOriginZ())
                    list->append(zoomAdjustedPixelValue(style.transformOriginZ(), style));
            }
            return WTFMove(list);
        }
        case CSSPropertyTransformStyle:
        case CSSPropertyWebkitTransformStyle:
            return cssValuePool.createIdentifierValue((style.transformStyle3D() == TransformStyle3D::Preserve3D) ? CSSValuePreserve3d : CSSValueFlat);
        case CSSPropertyTransitionDelay:
            return delayValue(style.transitions());
        case CSSPropertyTransitionDuration:
            return durationValue(style.transitions());
        case CSSPropertyTransitionProperty:
            return transitionPropertyValue(style.transitions());
        case CSSPropertyTransitionTimingFunction:
            return timingFunctionValue(style.transitions());
        case CSSPropertyTransition: {
            if (auto* animationList = style.transitions()) {
                auto transitionsList = CSSValueList::createCommaSeparated();
                for (size_t i = 0; i < animationList->size(); ++i) {
                    auto list = CSSValueList::createSpaceSeparated();
                    auto& animation = animationList->animation(i);
                    list->append(createTransitionPropertyValue(animation));
                    list->append(cssValuePool.createValue(animation.duration(), CSSPrimitiveValue::CSS_S));
                    list->append(createTimingFunctionValue(*animation.timingFunction()));
                    list->append(cssValuePool.createValue(animation.delay(), CSSPrimitiveValue::CSS_S));
                    transitionsList->append(WTFMove(list));
                }
                return WTFMove(transitionsList);
            }

            auto list = CSSValueList::createSpaceSeparated();
            // transition-property default value.
            list->append(cssValuePool.createIdentifierValue(CSSValueAll));
            list->append(cssValuePool.createValue(Animation::initialDuration(), CSSPrimitiveValue::CSS_S));
            list->append(createTimingFunctionValue(Animation::initialTimingFunction()));
            list->append(cssValuePool.createValue(Animation::initialDelay(), CSSPrimitiveValue::CSS_S));
            return WTFMove(list);
        }
        case CSSPropertyPointerEvents:
            return cssValuePool.createValue(style.pointerEvents());
        case CSSPropertyWebkitLineGrid:
            if (style.lineGrid().isNull())
                return cssValuePool.createIdentifierValue(CSSValueNone);
            return cssValuePool.createValue(style.lineGrid(), CSSPrimitiveValue::CSS_STRING);
        case CSSPropertyWebkitLineSnap:
            return CSSPrimitiveValue::create(style.lineSnap());
        case CSSPropertyWebkitLineAlign:
            return CSSPrimitiveValue::create(style.lineAlign());
        case CSSPropertyWritingMode:
            return cssValuePool.createValue(style.writingMode());
        case CSSPropertyWebkitTextCombine:
            return cssValuePool.createValue(style.textCombine());
        case CSSPropertyWebkitTextOrientation:
            return CSSPrimitiveValue::create(style.textOrientation());
        case CSSPropertyWebkitLineBoxContain:
            return createLineBoxContainValue(style.lineBoxContain());
        case CSSPropertyAlt:
            return altTextToCSSValue(style);
        case CSSPropertyContent:
            return contentToCSSValue(style);
        case CSSPropertyCounterIncrement:
            return counterToCSSValue(style, propertyID);
        case CSSPropertyCounterReset:
            return counterToCSSValue(style, propertyID);
        case CSSPropertyWebkitClipPath: {
            auto* operation = style.clipPath();
            if (!operation)
                return cssValuePool.createIdentifierValue(CSSValueNone);
            if (is<ReferenceClipPathOperation>(*operation))
                return CSSPrimitiveValue::create(downcast<ReferenceClipPathOperation>(*operation).url(), CSSPrimitiveValue::CSS_URI);
            auto list = CSSValueList::createSpaceSeparated();
            if (is<ShapeClipPathOperation>(*operation)) {
                auto& shapeOperation = downcast<ShapeClipPathOperation>(*operation);
                list->append(valueForBasicShape(style, shapeOperation.basicShape()));
                if (shapeOperation.referenceBox() != CSSBoxType::BoxMissing)
                    list->append(cssValuePool.createValue(shapeOperation.referenceBox()));
            }
            if (is<BoxClipPathOperation>(*operation))
                list->append(cssValuePool.createValue(downcast<BoxClipPathOperation>(*operation).referenceBox()));
            return WTFMove(list);
        }
        case CSSPropertyShapeMargin:
            return cssValuePool.createValue(style.shapeMargin(), style);
        case CSSPropertyShapeImageThreshold:
            return cssValuePool.createValue(style.shapeImageThreshold(), CSSPrimitiveValue::CSS_NUMBER);
        case CSSPropertyShapeOutside:
            return shapePropertyValue(style, style.shapeOutside());
        case CSSPropertyFilter:
            return valueForFilter(style, style.filter());
        case CSSPropertyAppleColorFilter:
            return valueForFilter(style, style.appleColorFilter());
#if ENABLE(FILTERS_LEVEL_2)
        case CSSPropertyWebkitBackdropFilter:
            return valueForFilter(style, style.backdropFilter());
#endif
#if ENABLE(CSS_COMPOSITING)
        case CSSPropertyMixBlendMode:
            return cssValuePool.createValue(style.blendMode());
        case CSSPropertyIsolation:
            return cssValuePool.createValue(style.isolation());
#endif
        case CSSPropertyBackgroundBlendMode: {
            auto& layers = style.backgroundLayers();
            if (!layers.next())
                return cssValuePool.createValue(layers.blendMode());
            auto list = CSSValueList::createCommaSeparated();
            for (auto* currLayer = &layers; currLayer; currLayer = currLayer->next())
                list->append(cssValuePool.createValue(currLayer->blendMode()));
            return WTFMove(list);
        }
        case CSSPropertyBackground:
            return getBackgroundShorthandValue();
        case CSSPropertyBorder: {
            auto value = propertyValue(CSSPropertyBorderTop, DoNotUpdateLayout);
            const CSSPropertyID properties[3] = { CSSPropertyBorderRight, CSSPropertyBorderBottom, CSSPropertyBorderLeft };
            for (auto& property : properties) {
                if (!compareCSSValuePtr<CSSValue>(value, propertyValue(property, DoNotUpdateLayout)))
                    return nullptr;
            }
            return value;
        }
        case CSSPropertyBorderBottom:
            return getCSSPropertyValuesForShorthandProperties(borderBottomShorthand());
        case CSSPropertyBorderColor:
            return getCSSPropertyValuesForSidesShorthand(borderColorShorthand());
        case CSSPropertyBorderLeft:
            return getCSSPropertyValuesForShorthandProperties(borderLeftShorthand());
        case CSSPropertyBorderImage:
            return valueForNinePieceImage(style.borderImage());
        case CSSPropertyBorderRadius:
            return borderRadiusShorthandValue(style);
        case CSSPropertyBorderRight:
            return getCSSPropertyValuesForShorthandProperties(borderRightShorthand());
        case CSSPropertyBorderStyle:
            return getCSSPropertyValuesForSidesShorthand(borderStyleShorthand());
        case CSSPropertyBorderTop:
            return getCSSPropertyValuesForShorthandProperties(borderTopShorthand());
        case CSSPropertyBorderWidth:
            return getCSSPropertyValuesForSidesShorthand(borderWidthShorthand());
        case CSSPropertyColumnRule:
            return getCSSPropertyValuesForShorthandProperties(columnRuleShorthand());
        case CSSPropertyColumns:
            return getCSSPropertyValuesForShorthandProperties(columnsShorthand());
        case CSSPropertyListStyle:
            return getCSSPropertyValuesForShorthandProperties(listStyleShorthand());
        case CSSPropertyMargin:
            return getCSSPropertyValuesForSidesShorthand(marginShorthand());
        case CSSPropertyOutline:
            return getCSSPropertyValuesForShorthandProperties(outlineShorthand());
        case CSSPropertyPadding:
            return getCSSPropertyValuesForSidesShorthand(paddingShorthand());

#if ENABLE(CSS_SCROLL_SNAP)
        case CSSPropertyScrollSnapMargin:
            return getCSSPropertyValuesForSidesShorthand(scrollSnapMarginShorthand());
        case CSSPropertyScrollSnapMarginBottom:
            return zoomAdjustedPixelValueForLength(style.scrollSnapMarginBottom(), style);
        case CSSPropertyScrollSnapMarginTop:
            return zoomAdjustedPixelValueForLength(style.scrollSnapMarginTop(), style);
        case CSSPropertyScrollSnapMarginRight:
            return zoomAdjustedPixelValueForLength(style.scrollSnapMarginRight(), style);
        case CSSPropertyScrollSnapMarginLeft:
            return zoomAdjustedPixelValueForLength(style.scrollSnapMarginLeft(), style);
        case CSSPropertyScrollPadding:
            return getCSSPropertyValuesForSidesShorthand(scrollPaddingShorthand());
        case CSSPropertyScrollPaddingBottom:
            return zoomAdjustedPixelValueForLength(style.scrollPaddingBottom(), style);
        case CSSPropertyScrollPaddingTop:
            return zoomAdjustedPixelValueForLength(style.scrollPaddingTop(), style);
        case CSSPropertyScrollPaddingRight:
            return zoomAdjustedPixelValueForLength(style.scrollPaddingRight(), style);
        case CSSPropertyScrollPaddingLeft:
            return zoomAdjustedPixelValueForLength(style.scrollPaddingLeft(), style);
        case CSSPropertyScrollSnapType:
            return valueForScrollSnapType(style.scrollSnapType());
        case CSSPropertyScrollSnapAlign:
            return valueForScrollSnapAlignment(style.scrollSnapAlign());
#endif

#if ENABLE(CSS_TRAILING_WORD)
        case CSSPropertyAppleTrailingWord:
            return cssValuePool.createValue(style.trailingWord());
#endif

#if ENABLE(APPLE_PAY)
        case CSSPropertyApplePayButtonStyle:
            return cssValuePool.createValue(style.applePayButtonStyle());
        case CSSPropertyApplePayButtonType:
            return cssValuePool.createValue(style.applePayButtonType());
#endif

        /* Individual properties not part of the spec */
        case CSSPropertyBackgroundRepeatX:
        case CSSPropertyBackgroundRepeatY:
            break;

        // Length properties for SVG.
        case CSSPropertyCx:
            return zoomAdjustedPixelValueForLength(style.svgStyle().cx(), style);
        case CSSPropertyCy:
            return zoomAdjustedPixelValueForLength(style.svgStyle().cy(), style);
        case CSSPropertyR:
            return zoomAdjustedPixelValueForLength(style.svgStyle().r(), style);
        case CSSPropertyRx:
            return zoomAdjustedPixelValueForLength(style.svgStyle().rx(), style);
        case CSSPropertyRy:
            return zoomAdjustedPixelValueForLength(style.svgStyle().ry(), style);
        case CSSPropertyStrokeDashoffset:
            return zoomAdjustedPixelValueForLength(style.svgStyle().strokeDashOffset(), style);
        case CSSPropertyX:
            return zoomAdjustedPixelValueForLength(style.svgStyle().x(), style);
        case CSSPropertyY:
            return zoomAdjustedPixelValueForLength(style.svgStyle().y(), style);
        case CSSPropertyWebkitTextZoom:
            return cssValuePool.createValue(style.textZoom());

        case CSSPropertyPaintOrder:
            return paintOrder(style.paintOrder());
        case CSSPropertyStrokeLinecap:
            return CSSPrimitiveValue::create(style.capStyle());
        case CSSPropertyStrokeLinejoin:
            return CSSPrimitiveValue::create(style.joinStyle());
        case CSSPropertyStrokeWidth:
            return zoomAdjustedPixelValueForLength(style.strokeWidth(), style);
        case CSSPropertyStrokeColor:
            return currentColorOrValidColor(&style, style.strokeColor());
        case CSSPropertyStrokeMiterlimit:
            return CSSPrimitiveValue::create(style.strokeMiterLimit(), CSSPrimitiveValue::CSS_NUMBER);

        /* Unimplemented CSS 3 properties (including CSS3 shorthand properties) */
        case CSSPropertyAll:
        case CSSPropertyAnimation:
        case CSSPropertyWebkitTextEmphasis:
            break;

        /* Directional properties are resolved by resolveDirectionAwareProperty() before the switch. */
        case CSSPropertyBorderBlockEnd:
        case CSSPropertyBorderBlockEndColor:
        case CSSPropertyBorderBlockEndStyle:
        case CSSPropertyBorderBlockEndWidth:
        case CSSPropertyBorderBlockStart:
        case CSSPropertyBorderBlockStartColor:
        case CSSPropertyBorderBlockStartStyle:
        case CSSPropertyBorderBlockStartWidth:
        case CSSPropertyBorderInlineEnd:
        case CSSPropertyBorderInlineEndColor:
        case CSSPropertyBorderInlineEndStyle:
        case CSSPropertyBorderInlineEndWidth:
        case CSSPropertyBorderInlineStart:
        case CSSPropertyBorderInlineStartColor:
        case CSSPropertyBorderInlineStartStyle:
        case CSSPropertyBorderInlineStartWidth:
        case CSSPropertyMarginBlockEnd:
        case CSSPropertyMarginBlockStart:
        case CSSPropertyMarginInlineEnd:
        case CSSPropertyMarginInlineStart:
        case CSSPropertyPaddingBlockEnd:
        case CSSPropertyPaddingBlockStart:
        case CSSPropertyPaddingInlineEnd:
        case CSSPropertyPaddingInlineStart:
        case CSSPropertyBlockSize:
        case CSSPropertyInlineSize:
        case CSSPropertyMaxBlockSize:
        case CSSPropertyMaxInlineSize:
        case CSSPropertyMinBlockSize:
        case CSSPropertyMinInlineSize:
            ASSERT_NOT_REACHED();
            break;

        /* Unimplemented @font-face properties */
        case CSSPropertySrc:
        case CSSPropertyUnicodeRange:
        case CSSPropertyFontDisplay:
            break;

        /* Other unimplemented properties */
        case CSSPropertyPage: // for @page
        case CSSPropertyQuotes: // FIXME: needs implementation
        case CSSPropertySize: // for @page
            break;

        /* Unimplemented -webkit- properties */
        case CSSPropertyWebkitBorderRadius:
        case CSSPropertyWebkitMarginCollapse:
        case CSSPropertyWebkitMarquee:
        case CSSPropertyWebkitMarqueeSpeed:
        case CSSPropertyWebkitMask:
        case CSSPropertyWebkitMaskRepeatX:
        case CSSPropertyWebkitMaskRepeatY:
        case CSSPropertyPerspectiveOriginX:
        case CSSPropertyPerspectiveOriginY:
        case CSSPropertyWebkitTextStroke:
        case CSSPropertyTransformOriginX:
        case CSSPropertyTransformOriginY:
        case CSSPropertyTransformOriginZ:
            break;

#if ENABLE(CSS_DEVICE_ADAPTATION)
        case CSSPropertyMaxZoom:
        case CSSPropertyMinZoom:
        case CSSPropertyOrientation:
        case CSSPropertyUserZoom:
            break;
#endif

        case CSSPropertyBufferedRendering:
        case CSSPropertyClipPath:
        case CSSPropertyClipRule:
        case CSSPropertyMask:
        case CSSPropertyEnableBackground:
        case CSSPropertyFloodColor:
        case CSSPropertyFloodOpacity:
        case CSSPropertyLightingColor:
        case CSSPropertyStopColor:
        case CSSPropertyStopOpacity:
        case CSSPropertyColorInterpolation:
        case CSSPropertyColorInterpolationFilters:
        case CSSPropertyColorProfile:
        case CSSPropertyColorRendering:
        case CSSPropertyFill:
        case CSSPropertyFillOpacity:
        case CSSPropertyFillRule:
        case CSSPropertyMarker:
        case CSSPropertyMarkerEnd:
        case CSSPropertyMarkerMid:
        case CSSPropertyMarkerStart:
        case CSSPropertyMaskType:
        case CSSPropertyShapeRendering:
        case CSSPropertyStroke:
        case CSSPropertyStrokeDasharray:
        case CSSPropertyStrokeOpacity:
        case CSSPropertyAlignmentBaseline:
        case CSSPropertyBaselineShift:
        case CSSPropertyDominantBaseline:
        case CSSPropertyGlyphOrientationHorizontal:
        case CSSPropertyGlyphOrientationVertical:
        case CSSPropertyKerning:
        case CSSPropertyTextAnchor:
        case CSSPropertyVectorEffect:
        case CSSPropertyWebkitSvgShadow:
            return svgPropertyValue(propertyID, DoNotUpdateLayout);
        case CSSPropertyCustom:
            ASSERT_NOT_REACHED();
            return nullptr;
    }

    logUnimplementedPropertyID(propertyID);
    return nullptr;
}

String CSSComputedStyleDeclaration::getPropertyValue(CSSPropertyID propertyID) const
{
    auto value = getPropertyCSSValue(propertyID);
    if (!value)
        return emptyString(); // FIXME: Should this be null instead, as it is in StyleProperties::getPropertyValue?
    return value->cssText();
}

unsigned CSSComputedStyleDeclaration::length() const
{
    updateStyleIfNeededForProperty(m_element.get(), CSSPropertyCustom);

    auto* style = m_element->computedStyle(m_pseudoElementSpecifier);
    if (!style)
        return 0;

    return numComputedProperties + style->customProperties().size();
}

String CSSComputedStyleDeclaration::item(unsigned i) const
{
    if (i >= length())
        return String();

    if (i < numComputedProperties)
        return getPropertyNameString(computedProperties[i]);

    auto* style = m_element->computedStyle(m_pseudoElementSpecifier);
    if (!style)
        return String();

    unsigned index = i - numComputedProperties;

    const auto& customProperties = style->customProperties();
    if (index >= customProperties.size())
        return String();

    auto results = copyToVector(customProperties.keys());
    return results.at(index);
}

bool ComputedStyleExtractor::propertyMatches(CSSPropertyID propertyID, const CSSValue* value)
{
    if (!m_element)
        return false;
    if (propertyID == CSSPropertyFontSize && is<CSSPrimitiveValue>(*value)) {
        m_element->document().updateLayoutIgnorePendingStylesheets();
        if (auto* style = m_element->computedStyle(m_pseudoElementSpecifier)) {
            if (CSSValueID sizeIdentifier = style->fontDescription().keywordSizeAsIdentifier()) {
                auto& primitiveValue = downcast<CSSPrimitiveValue>(*value);
                if (primitiveValue.isValueID() && primitiveValue.valueID() == sizeIdentifier)
                    return true;
            }
        }
    }
    RefPtr<CSSValue> computedValue = propertyValue(propertyID);
    return computedValue && value && computedValue->equals(*value);
}

Ref<MutableStyleProperties> ComputedStyleExtractor::copyProperties()
{
    return copyPropertiesInSet(computedProperties, numComputedProperties);
}

RefPtr<CSSValueList> ComputedStyleExtractor::getCSSPropertyValuesForShorthandProperties(const StylePropertyShorthand& shorthand)
{
    auto list = CSSValueList::createSpaceSeparated();
    for (size_t i = 0; i < shorthand.length(); ++i)
        list->append(propertyValue(shorthand.properties()[i], DoNotUpdateLayout).releaseNonNull());
    return WTFMove(list);
}

RefPtr<CSSValueList> ComputedStyleExtractor::getCSSPropertyValuesForSidesShorthand(const StylePropertyShorthand& shorthand)
{
    auto list = CSSValueList::createSpaceSeparated();

    // Assume the properties are in the usual order top, right, bottom, left.
    auto topValue = propertyValue(shorthand.properties()[0], DoNotUpdateLayout);
    auto rightValue = propertyValue(shorthand.properties()[1], DoNotUpdateLayout);
    auto bottomValue = propertyValue(shorthand.properties()[2], DoNotUpdateLayout);
    auto leftValue = propertyValue(shorthand.properties()[3], DoNotUpdateLayout);

    // All 4 properties must be specified.
    if (!topValue || !rightValue || !bottomValue || !leftValue)
        return nullptr;

    bool showLeft = !compareCSSValuePtr(rightValue, leftValue);
    bool showBottom = !compareCSSValuePtr(topValue, bottomValue) || showLeft;
    bool showRight = !compareCSSValuePtr(topValue, rightValue) || showBottom;

    list->append(topValue.releaseNonNull());
    if (showRight)
        list->append(rightValue.releaseNonNull());
    if (showBottom)
        list->append(bottomValue.releaseNonNull());
    if (showLeft)
        list->append(leftValue.releaseNonNull());

    return WTFMove(list);
}

RefPtr<CSSValueList> ComputedStyleExtractor::getCSSPropertyValuesForGridShorthand(const StylePropertyShorthand& shorthand)
{
    auto list = CSSValueList::createSlashSeparated();
    for (size_t i = 0; i < shorthand.length(); ++i)
        list->append(propertyValue(shorthand.properties()[i], DoNotUpdateLayout).releaseNonNull());
    return WTFMove(list);
}

Ref<MutableStyleProperties> ComputedStyleExtractor::copyPropertiesInSet(const CSSPropertyID* set, unsigned length)
{
    Vector<CSSProperty, 256> list;
    list.reserveInitialCapacity(length);
    for (unsigned i = 0; i < length; ++i) {
        if (auto value = propertyValue(set[i]))
            list.append(CSSProperty(set[i], WTFMove(value), false));
    }
    return MutableStyleProperties::create(list.data(), list.size());
}

CSSRule* CSSComputedStyleDeclaration::parentRule() const
{
    return nullptr;
}

RefPtr<DeprecatedCSSOMValue> CSSComputedStyleDeclaration::getPropertyCSSValue(const String& propertyName)
{
    if (isCustomPropertyName(propertyName)) {
        auto value = ComputedStyleExtractor(m_element.ptr(), m_allowVisitedStyle, m_pseudoElementSpecifier).customPropertyValue(propertyName);
        if (!value)
            return nullptr;
        return value->createDeprecatedCSSOMWrapper(*this);
    }

    CSSPropertyID propertyID = cssPropertyID(propertyName);
    if (!propertyID)
        return nullptr;
    auto value = getPropertyCSSValue(propertyID);
    if (!value)
        return nullptr;
    return value->createDeprecatedCSSOMWrapper(*this);
}

String CSSComputedStyleDeclaration::getPropertyValue(const String &propertyName)
{
    if (isCustomPropertyName(propertyName))
        return ComputedStyleExtractor(m_element.ptr(), m_allowVisitedStyle, m_pseudoElementSpecifier).customPropertyText(propertyName);

    CSSPropertyID propertyID = cssPropertyID(propertyName);
    if (!propertyID)
        return String();
    return getPropertyValue(propertyID);
}

String CSSComputedStyleDeclaration::getPropertyPriority(const String&)
{
    // All computed styles have a priority of not "important".
    return emptyString(); // FIXME: Should this sometimes be null instead of empty, to match a normal style declaration?
}

String CSSComputedStyleDeclaration::getPropertyShorthand(const String&)
{
    return emptyString(); // FIXME: Should this sometimes be null instead of empty, to match a normal style declaration?
}

bool CSSComputedStyleDeclaration::isPropertyImplicit(const String&)
{
    return false;
}

ExceptionOr<void> CSSComputedStyleDeclaration::setProperty(const String&, const String&, const String&)
{
    return Exception { NoModificationAllowedError };
}

ExceptionOr<String> CSSComputedStyleDeclaration::removeProperty(const String&)
{
    return Exception { NoModificationAllowedError };
}

RefPtr<CSSValue> CSSComputedStyleDeclaration::getPropertyCSSValueInternal(CSSPropertyID propertyID)
{
    return getPropertyCSSValue(propertyID);
}

String CSSComputedStyleDeclaration::getPropertyValueInternal(CSSPropertyID propertyID)
{
    return getPropertyValue(propertyID);
}

ExceptionOr<bool> CSSComputedStyleDeclaration::setPropertyInternal(CSSPropertyID, const String&, bool)
{
    return Exception { NoModificationAllowedError };
}

Ref<CSSValueList> ComputedStyleExtractor::getBackgroundShorthandValue()
{
    static const CSSPropertyID propertiesBeforeSlashSeperator[5] = { CSSPropertyBackgroundColor, CSSPropertyBackgroundImage, CSSPropertyBackgroundRepeat, CSSPropertyBackgroundAttachment, CSSPropertyBackgroundPosition };
    static const CSSPropertyID propertiesAfterSlashSeperator[3] = { CSSPropertyBackgroundSize, CSSPropertyBackgroundOrigin, CSSPropertyBackgroundClip };

    auto list = CSSValueList::createSlashSeparated();
    list->append(*getCSSPropertyValuesForShorthandProperties(StylePropertyShorthand(CSSPropertyBackground, propertiesBeforeSlashSeperator)));
    list->append(*getCSSPropertyValuesForShorthandProperties(StylePropertyShorthand(CSSPropertyBackground, propertiesAfterSlashSeperator)));
    return list;
}

} // namespace WebCore
