Parse and add experimental flag for content-visibility

[rwlbuis]

23a0b63

Parse and add experimental flag for content-visibility
https://bugs.webkit.org/show_bug.cgi?id=236371

Reviewed by NOBODY (OOPS!).

Split out the parsing code out of the prototype patch and add experiment flag for content-visibility.

* LayoutTests/imported/w3c/web-platform-tests/css/css-cascade/all-prop-initial-xml-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-contain/content-visibility/content-visibility-026-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-contain/content-visibility/content-visibility-077-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-contain/content-visibility/inheritance-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-contain/content-visibility/parsing/content-visibility-computed-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/css-contain/content-visibility/parsing/content-visibility-valid-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree-expected.txt:
* LayoutTests/platform/gtk/imported/w3c/web-platform-tests/css/css-cascade/all-prop-initial-xml-expected.txt:
* LayoutTests/platform/gtk/imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree-expected.txt:
* LayoutTests/platform/ios/imported/w3c/web-platform-tests/css/cssom/getComputedStyle-detached-subtree-expected.txt:
* LayoutTests/platform/wpe/imported/w3c/web-platform-tests/css/css-cascade/all-prop-initial-xml-expected.txt:
* Source/WTF/Scripts/Preferences/WebPreferencesExperimental.yaml:
* Source/WebCore/animation/CSSPropertyAnimation.cpp:
(WebCore::CSSPropertyAnimationWrapperMap::CSSPropertyAnimationWrapperMap):
* Source/WebCore/css/CSSComputedStyleDeclaration.cpp:
(WebCore::ComputedStyleExtractor::valueForPropertyInStyle):
* Source/WebCore/css/CSSPrimitiveValueMappings.h:
(WebCore::CSSPrimitiveValue::CSSPrimitiveValue):
(WebCore::CSSPrimitiveValue::operator ContentVisibility const):
* Source/WebCore/css/CSSProperties.json:
* Source/WebCore/css/parser/CSSParserContext.cpp:
(WebCore::operator==):
(WebCore::add):
* Source/WebCore/css/parser/CSSParserContext.h:
* Source/WebCore/css/parser/CSSPropertyParser.cpp:
(WebCore::consumeContentVisibility):
(WebCore::CSSPropertyParser::parseSingleValue):
* Source/WebCore/rendering/RenderObject.cpp:
(WebCore::RenderObject::setLayoutContainmentApplies):
(WebCore::RenderObject::RenderObjectRareData::RenderObjectRareData):
* Source/WebCore/rendering/RenderObject.h:
(WebCore::RenderObject::layoutContainmentApplies const):
* Source/WebCore/rendering/style/RenderStyle.h:
(WebCore::RenderStyle::contentVisibility const):
(WebCore::RenderStyle::contentVisibilityHidden const):
(WebCore::RenderStyle::setContentVisibility):
(WebCore::RenderStyle::initialContentVisibility):
* Source/WebCore/rendering/style/RenderStyleConstants.h:
* Source/WebCore/rendering/style/StyleRareNonInheritedData.cpp:
(WebCore::StyleRareNonInheritedData::StyleRareNonInheritedData):
(WebCore::StyleRareNonInheritedData::operator== const):
* Source/WebCore/rendering/style/StyleRareNonInheritedData.h: