Bug 247884 – [css-transitions] setting transition-property to "none" does not disassociate CSS Transition from owning element

• Component: Animations
• Status: RESOLVED FIXED

[Antoine Quint]

We are failing a subtest in web-animations/timing-model/timelines/update-and-send-events-replacement.html:

promise_test(async t => {
  // Setup transition
  const div = createDiv(t);
  div.style.opacity = '0';
  div.style.transition = 'opacity 1ms';
  getComputedStyle(div).opacity;
  div.style.opacity = '1';
  const cssTransition = div.getAnimations()[0];
  cssTransition.effect.updateTiming({ fill: 'forwards' });

  // Break tie to markup
  div.style.transitionProperty = 'none';
  assert_equals(cssTransition.playState, 'idle');

  // Restart transition
  cssTransition.play();

  const scriptAnimation = div.animate(
    { opacity: 1 },
    {
      duration: 1,
      fill: 'forwards',
    }
  );
  await scriptAnimation.finished;

  assert_equals(cssTransition.replaceState, 'removed');
  assert_equals(scriptAnimation.replaceState, 'active');
}, 'Removes a CSS transition no longer tied to markup');

We fail the second-to-last assertion because we do not correctly disassociate a CSS Transition from its owning element when transition-property is set to "none" and thus do not mark that transition as replaceable.

[Antoine Quint]

Pull request: https://github.com/WebKit/WebKit/pull/6465

[EWS]

Committed 256666@main (7821448df0f4): <https://commits.webkit.org/256666@main>

Reviewed commits have been landed. Closing PR #6465 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/102333068>