http://jsfiddle.net/8Lv88/ As shown on this fiddle, when you click the image, corners appear during and after the transition performed on the images opacity. I encountered this bug on latest Chrome and Safari mobile.
Yeah, we don't get the rounded clipping right when we do compositing. I thought we had another bug on this.
Still experiencing this in 2017. Any progress? :)
<rdar://problem/32746949>
rdar://problem/32685406
the test case doesn't work anymore. I forked it and replaced the images. http://jsfiddle.net/fujihiro/y1cL6kdx/3/
the latest Safari seems to work nicely.