Clear animations in DisplayLists when done

The matrix calculated by Animations is pushed down to the native
DisplayList object, and is then used when the DL is issued to the
GL renderer. This works while the animation is running, but the end
of animations is not handled correctly. In particular, we never clear the
animation, so whatever the last frame of the animation calculated will
persist on that DisplayList object until it is recreated.

The fix is to note when we used to be animating and are no longer
doing so, taking that opportunity to push the cleared state down
to the DisplayList.

Issue #6448993 action bar -- including settings menu -- disappears on Nakasi

Change-Id: I73cdadaef40d87ccbc1beb02599c4d70506ea42b