Allow gestures to executed started from deadzone on nav bar

Set slippery to true when gesture starts from deadzone and when finished
set slippery to its correct state.

Change-Id: I035d12f9639ce4af00db9e0d25b514f074b5198c
Fixes: 78886558
Test: swipe up from deadzone on nav bar (just above home button)
1 file changed