SystemUI: Restore bounds when loading new gradient

This fixes an issue introduced with the reloading of the nav bar
transitions after a theme change in Change-Id: I256afc30fc018ea752769029c5246bc7310c23a6

Change-Id: I648039506b826583d554b2a0cf4f6ab9a9bb1de8

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/BarTransitions.java