WIP: Update browser ui to new design

TODOS:
- Marking favorite from favorite grid or from tab view is
not using the same code path as adding favorite to launcher
- Tab model doesn't persist received favicons. Bookmarking
a non-loaded tab after browser restart does not work.
- Overlay transition occasionally misses many frames. Happens when
dragging overlay open.
- FavoriteContextMenu is not used in Tab view
- TabView UI needs tuning
- Broke back button handling