Revert "Revert "Speed up All Apps -> Workspace transition""

- also, undo enabling hardware layers for
    scroll indicator, which could have caused
    slowness
- fix bug where scroll indicator was not seen
    after the first visit to all apps
- eliminate a some needless hardware layer redraws
- making items under All Apps invisible when we're
    in All Apps
- making workspace spaces invisible if their alpha is 0
    to prevent more hardware layer rebuilding

This reverts commit 9753d13c7bda09c1203c611ac6717021037f39c3.

Change-Id: Ib908ae0b456b2d4b8a171991a95f20aea4749da1
5 files changed