Run animation *after* property sync

VectorDrawable contains properties that can be mofidied from both
UI thread and RenderThread. The two sets of properties are synced
during prepareTree. Previously VD animations ran before prepareTree,
as a result, during prepareTree the property sync overwrote some
of the animatable properties. In other words, the first frame of
the animation wasn't correct. An example is in battery saver mode
when the animation only has one frame to animate (0-duration), the
end result looked wrong.

This CL moves the VD animation to after prepareTree to solve the
problem mentioned above. Meanwhile, in order to signal which
VD will be animated so as to have them properly damaged, all VDs
with running animators are marked dirty.

Bug: 30226711
Change-Id: I831dae9abb2908876c935b9be4c11dfd09452d5c