[scroll-animations] make animation-timeline, animation-range-start and animation-range-end reset-only longhands of the animation shorthand

[graouts]

91fb05a

[scroll-animations] make `animation-timeline`, `animation-range-start` and `animation-range-end` reset-only longhands of the `animation` shorthand
https://bugs.webkit.org/show_bug.cgi?id=287398

Reviewed by Tim Nguyen.

The CSS WG resolved in w3c/csswg-drafts#6946 (comment) to make the
new CSS properties introduced to support Scroll-driven Animations – `animation-timeline`, `animation-range-start`
and `animation-range-end` – reset-only longhands of the `animation` shorthand.

To that end, we add those properties to the `"longhands"` property for `animation` in `CSSProperties.json`
and deal with them when relevant:

- in `CSSPropertyParser.cpp` we set `nullptr` values for those properties to reset any value previously set
and ensure those properties have the right initial values for serialization purposes.

- in `ComputedStyleExtractor.cpp` we return an empty value whenever we attempt to serialize the `animation`
shorthand in the computed style when one of those reset-only longhands was otherwise set.

- in `ShorthandSerializer.cpp` we do similar work when serializing the specified value.

* LayoutTests/imported/w3c/web-platform-tests/css/css-animations/parsing/animation-shorthand-expected.txt:
* LayoutTests/imported/w3c/web-platform-tests/scroll-animations/css/animation-shorthand-expected.txt:
* Source/WebCore/css/CSSProperties.json:
* Source/WebCore/css/ComputedStyleExtractor.cpp:
(WebCore::animationShorthandValue):
* Source/WebCore/css/ShorthandSerializer.cpp:
(WebCore::ShorthandSerializer::serializeLayered const):
* Source/WebCore/css/parser/CSSPropertyParser.cpp:
(WebCore::initialValueForLonghand):
(WebCore::consumeAnimationValueForShorthand):
(WebCore::CSSPropertyParser::consumeAnimationShorthand):

Canonical link: https://commits.webkit.org/290168@main

260cd38

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	🧪 mac-intel-wk2	✅ 🛠 playstation
✅ 🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 8656c6a)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2	🧪 win-tests
✅ 🧪 webkitperl	🧪 ios-wk2	🧪 api-mac	🧪 api-wpe
	🧪 ios-wk2-wpt	⏳ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	🧪 api-ios	🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 vision-sim	⏳ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
	🧪 vision-wk2	⏳ 🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 260cd38)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	✅ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	🧪 mac-wk2-stress	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	🧪 mac-intel-wk2	✅ 🛠 playstation
✅ 🛠 🧪 unsafe-merge	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 290168@main (91fb05a): https://commits.webkit.org/290168@main

Reviewed commits have been landed. Closing PR #40351 and removing active labels.