Left handed navbar: fix keyboard placement in immersive mode

when using immersive mode with left handed navbar in landscape the keyboard doesn't account for
the navbar appearing from the left and leaves an empty layer on the right, we need to use mStableLeft
so it takes its position accordingly.

Change-Id: I937e46661673b8560357afd4cbd7289bae87734f
(cherry picked from commit 7eece5bbf1b20951f28682259982364ac678c602)
SystemUI: Rework SearchPanelView calculations

Make isScreenLarge calculations match how the system calculates where to put the navigation
bar. This fixes certain cases where the quick launch buttons on the glowpad of the
navigation bar is improperly oriented.

Patch set 2: The eval should be greater OR EQUAL to 600, not just greater. Also cache result
into a boolean before returning it.

Patch set 3-4: Actually cache it this time.

Patch set 5-6: Make it final.

Change-Id: I5703578b4d49a6eeab100bb23167abd5cf9a326d
(cherry picked from commit 11324a2d39970683c2cb90dd0c909db91ce86a85)