Ime in gestural mode will have ime switcher and down arrow

When in gestural mode, the navigation bar will inset the ime window
higher to raise up revealing the original height of the navigation bar.
In place will be the (alt) back button (pointing down), the handle and
ime switcher (if should be shown).

Fixes: 128928130
Bug: 113952590
Bug: 112934365
Test: manual
Change-Id: I28cc4def846cb09eb2d7ab00d12561f0c198dbbc