ZoomIn transition animation fails in some condition on Android

[ykami]

ZoomIn transition animation fails in some condition. Once it fails, no transition works without reloading the page.

You can reproduced this issue on test_transition_animation.html with the following steps:

1. Click "Extended Transitions 4"
2. Click "Zoom In" in View1, then transition to View2.
3. Click "Zoom In" in View2, then transition to View3, but just after that, the view replaced by View2. Once this occurs, no transition works in the view.

It seems that, during zoomInOut animation, webkitAnimationStart event is always fired but webkitAnimationEnd event is sometimes not fired. This only occurs in zoomIn animation, not in scaleIn animation which has the same CSS animation styles.

(reported by onoat)

[ykami]

In [26456]:

Fixes #13824 !strict. Empty keyframes like from {} to {} causes a problem at least on Android. Workaround is to give the same transform to both from and to. Thank you onoat for finding this workaround.