If an animation's keyframes affect stacking context properties, create stacking context while the animation is running
Created attachment 293077 [details]
*** Bug 66341 has been marked as a duplicate of this bug. ***
Comment on attachment 293077 [details]
View in context: https://bugs.webkit.org/attachment.cgi?id=293077&action=review
> - dst->setOpacity(blendFunc(anim, (fromOpacity == 1) ? 0.999999f : fromOpacity, b->opacity(), progress));
> + dst->setOpacity(blendFunc(anim, a->opacity(), b->opacity(), progress));
Glad to see this go.
> + blendedStyle->setZIndex(0);
It would be nice if there was a more obvious way to mark as needing a stacking context.