nsFrame::SchedulePaint() invokes InvalidateRenderingObservers, and
InvalidateRenderingObservers ends up posting change hints during we are
processing sequential tasks for animations, but we don't allow posting any
change hints while we are in the middle of restyling process.
Though the change hints posted by InvalidateRenderingObservers are not harmful
in this case since the change hints will be processed in a second post
traversal without problems. That's said, InvalidateRenderingObservers stuff
should be processed in display list based invalidation anyway (bug 1284053).
MozReview-Commit-ID: GKVRZ98lvEN
The approach here is to lazily check if we have such animations. This allows
animations to be modified after being added to the pending animation tracker
(but not after HasPlayPendingGeometricAnimations is called since we cache the
result at that point) and avoids poor performance when calling
RemovePlayPending.
MozReview-Commit-ID: LRLpCRnzvw
This is in anticipation of adding Animation::SetTimeline(). Once we set the
timeline out of band, there's a chance that getting it could return null so
this patch makes the WebIDL and method name reflect that.
This is not strictly necessary yet but we will want to implement methods
like GetAnimations() on the base class, AnimationTimeline, so we may as well do
that now rather than adding that code to DocumentTimeline and moving it later.
