<rdar://problem/56820674>
Created attachment 396549 [details] Patch
Found 4 new test failures: imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/style-change-events.html, imported/w3c/web-platform-tests/web-animations/interfaces/Animatable/animate.html, imported/w3c/web-platform-tests/web-animations/interfaces/KeyframeEffect/target.html, imported/w3c/web-platform-tests/web-animations/interfaces/Animation/commitStyles.html
Committed r260147: <https://trac.webkit.org/changeset/260147>