The test css/css-animations/KeyframeEffect-getKeyframes.tentative.html was changed recently in https://github.com/web-platform-tests/wpt/commit/1a5c61d2ca9d0f2c2801adf2b433c7931512152f to account for the `animation-composition` property. We need to update our implementation to pass this test, or indicate whether it is incorrect.
*** This bug has been marked as a duplicate of bug 251499 ***