The test web-animations/timing-model/animations/seamlessly-updating-the-playback-rate-of-an-animation.html has one failure reported on WPT.fyi: https://wpt.fyi/results/web-animations/timing-model/animations/seamlessly-updating-the-playback-rate-of-an-animation.html?label=experimental&label=master&aligned. This is due to a spec change that occurred in https://github.com/w3c/csswg-drafts/pull/7148/files. We need to update our implementation and re-import this test to pick up the new subtest that is currently failing.