[animation-triggers] add parsing support for the `timeline-trigger-active-range` shorthand

https://bugs.webkit.org/show_bug.cgi?id=319418
rdar://182243126

Reviewed by Brent Fulgham.

The animation-triggers spec adds a new shorthand property: `timeline-trigger-active-range`.

* LayoutTests/imported/w3c/web-platform-tests/scroll-animations/animation-trigger/parsing/timeline-trigger-active-range-shorthand.tentative-expected.txt:
* Source/WebCore/css/CSSProperties.json:
* Source/WebCore/css/ShorthandSerializer.cpp:
(WebCore::ShorthandSerializer::serialize):
* Source/WebCore/css/parser/CSSPropertyParserCustom.h:
(WebCore::CSS::PropertyParserCustom::consumeTimelineTriggerActiveRangeShorthand):
* Source/WebCore/style/StyleExtractorCustom.h:
(WebCore::Style::ExtractorCustom::extractTimelineTriggerActiveRangeShorthand):
(WebCore::Style::ExtractorCustom::extractTimelineTriggerActiveRangeShorthandSerialization):
* Source/WebCore/style/values/animation-triggers/StyleTimelineTrigger.h:
(WebCore::Style::TimelineTrigger::initialActiveRange):
(WebCore::Style::TimelineTrigger::activeRange const):
(WebCore::Style::TimelineTrigger::setActiveRange):
(WebCore::Style::TimelineTrigger::fillActiveRange):
(WebCore::Style::TimelineTrigger::clearActiveRange):
(WebCore::Style::TimelineTrigger::isActiveRangeUnset const):
(WebCore::Style::TimelineTrigger::isActiveRangeSet const):
(WebCore::Style::TimelineTrigger::isActiveRangeFilled const):

Canonical link: https://commits.webkit.org/317291@main