PIP: Fix regressions

This includes following fixes
- Press back key to go to Home from Recents
- Do not show Recents when an activity is PIPed immediately after moved
  to fullscreen.

These regressions are caused by
c81082b7 Improve Animation Calculations to remove Jank

Bug: 28107787
Change-Id: I3078a5d8a9505c8d03cceee329e5d740efae7feb