Created attachment 276694 [details] Testcase In the attached test case, hover the box and wait for the animation to finish. Then un-hover and re-hover. Note how the animation restarts. In other browsers, the animation does not restart, which is correct because the animation-name property still applies to the element. Our mistake is to completely remove finished animations in CompositeAnimation::updateKeyframeAnimations(). We need to keep some state around to know that we shouldn't re-run this animation when play-state changes.
Created attachment 277219 [details] Patch
Created attachment 277273 [details] Patch
Comment on attachment 277273 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=277273&action=review > Source/WebCore/ChangeLog:14 > + Fix by keeping state for keyframe animations in the Done state in the m_keyframeAnimations > + map. This allows for the removal of the You forgot to end this sentence
https://trac.webkit.org/r200047
This change appears to have caused fast/layers/no-clipping-overflow-hidden-added-after-transform.html to fail on mac-wk1 debug https://build.webkit.org/results/Apple%20El%20Capitan%20Debug%20WK1%20%28Tests%29/r200051%20%284689%29/results.html