Add animation to running animation list before starting.

The animation needs to be added to the animation list before starting
to ensure it's in the list before onAnimationEnd is called. Specifically,
this can happen if the duration is 0 since the animation will complete
very quickly. If that occurs, the animation will be added to the list
after it's been "removed" which means there will continue to be a reference
to that animation even after it's completed.

Also fix a few other issues:
1. Don't create a dim layer if stopDim is called. This causes excess
layers to be created, just so they can be destroyed.
2. Add try/catch to dim layer create so the system doesn't crash if the
layer fails to create.

Test: Enter split screen and move divider so dim layers are show and
hidden. There are no longer excess dim layers being created and leashes
are being properly dereferenced.
Fixes: 80206408

Change-Id: I7198bd5e972fce32633869697a4d26f51e675d48