Ensures that we end back to home animation on the last animation frame.

This fixes the bug where user performs double swipe back to home and we
have a floating window on the screen.

Fixes: 277515917
Test: From an app, back swipe to home, and then immediately back swipe
      to home again
Flag: NONE
Change-Id: If312ee55efeaadde896511c6d449826368b15a84