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.