[webkit-changes] [WebKit/WebKit] 7687d0: REGRESSION(270890 at main): Animation doesn't trigger...

[Antti Koivisto]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7687d03911da56a6689087f88c4812174ef2febe
      https://github.com/WebKit/WebKit/commit/7687d03911da56a6689087f88c4812174ef2febe
  Author: Antti Koivisto <antti at apple.com>
  Date:   2023-11-29 (Wed, 29 Nov 2023)

  Changed paths:
    A LayoutTests/imported/w3c/web-platform-tests/css/css-animations/animation-css-variable-dependent-property-expected.txt
    A LayoutTests/imported/w3c/web-platform-tests/css/css-animations/animation-css-variable-dependent-property.html
    M Source/WebCore/style/StyleTreeResolver.cpp

  Log Message:
  -----------
  REGRESSION(270890 at main): Animation doesn't trigger when custom property initial value matches the first frame
https://bugs.webkit.org/show_bug.cgi?id=265160
rdar://118697176

Reviewed by Antoine Quint.

If the initial value of a declared custom property is the same as the first frame we would bail out before
computing the cascade effect (since nothing changes). Because of this we would fail to set hasPropertiesOverridenAfterAnimation
bit and then proceed to optimize away the cascade updates for future frames too.

* LayoutTests/imported/w3c/web-platform-tests/css/css-animations/animation-css-variable-dependent-property-expected.txt: Added.
* LayoutTests/imported/w3c/web-platform-tests/css/css-animations/animation-css-variable-dependent-property.html: Added.
* Source/WebCore/style/StyleTreeResolver.cpp:
(WebCore::Style::TreeResolver::createAnimatedElementUpdate):

Ensure that we apply the cascade when computing the first frame of animation so we know to not optimize away style
updates for the subsequent frames.

Canonical link: https://commits.webkit.org/271268@main