Allow translucent navigation bar in landscape mode.

Change-Id: I5388f3f8a34533624619714bacfba52f95fc6d85
Fix glitch appearing when using translucent system bars in landscape.

Before: http://i.imgur.com/zJCjCvx.png
After: http://i.imgur.com/v563Shz.png

Change-Id: I0580ced6dcd614239ea0815bc9943c9bbe86eb99

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