Don't hide the home handle when it is attaching to the app

We had the logic in the case of legacy transition. This CL applies it to
the shell transition cases.

Fix: 286222508
Fix: 283037901
Test: Open Calculator in landscape and drag the home handle up. See if
      the home handle attaches to the app when dragging.
Test: Open Calculator in portrait and swipe home handle up to enter
      overview screen. See if there is a fade-in animation when home
      handle is showing at the screen bottom.
Change-Id: Ib1321532ebbef57f2d371344f895b9ee3a58a28d