[webkit-changes] [WebKit/WebKit] 4a38bb: [web-animations] accelerated CSS Animation should ...

[Antoine Quint]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 4a38bbbd7547d45a97ce02294621513d1559ce7a
      https://github.com/WebKit/WebKit/commit/4a38bbbd7547d45a97ce02294621513d1559ce7a
  Author: Antoine Quint <graouts at webkit.org>
  Date:   2023-12-06 (Wed, 06 Dec 2023)

  Changed paths:
    A LayoutTests/webanimations/scheduling-of-accelerated-css-animation-without-css-animation-event-listeners-expected.txt
    A LayoutTests/webanimations/scheduling-of-accelerated-css-animation-without-css-animation-event-listeners.html
    M Source/WebCore/animation/KeyframeEffect.cpp

  Log Message:
  -----------
  [web-animations] accelerated CSS Animation should not schedule animation resolution at iteration boundary if no CSS Animation event listener was registered (affects reddit.com)
https://bugs.webkit.org/show_bug.cgi?id=265936
rdar://119244430

Reviewed by Antti Koivisto.

While we don't need to schedule animation resolution for animations that are running accelerated
to resolve styles, we do need to schedule resolution in order to dispatch `animationiteration`
events in the case of CSS Animations.

However, it is unlikely that the content will be interested in such events. As a cheap optimization,
we can detect whether any CSS Animation event listener is registered for the document to which the
effect target belongs, and if that is not the case we don't need to schedule animation resolution.

* LayoutTests/webanimations/scheduling-of-accelerated-css-animation-without-css-animation-event-listeners-expected.txt: Added.
* LayoutTests/webanimations/scheduling-of-accelerated-css-animation-without-css-animation-event-listeners.html: Added.
* Source/WebCore/animation/KeyframeEffect.cpp:
(WebCore::KeyframeEffect::timeToNextTick const):

Canonical link: https://commits.webkit.org/271604@main