Don't notify windows of resize during PIP animation.

We are notifying windows of resize as the frame moves (even though the
size does not change) during the pinned animation, confusing and
upsetting the client. We do want to notify it of the one resize
at the beginning or end of the animation, so we can't just block
reportResized on bounds animating. Luckily the other area that adds
windows to reportResized (Task) is smart enough to only do so if the
size has actually changed and not just movement, so we let those reports
go through and block ones initiating from here (which doesn't perform
a check that the size has actually changed).

Bug: 28559097
Change-Id: If1f983e7cc875175ce1d098c385478a9922dea67