Make wake-and-unlock faster

- Scrims: When dismissing Keyguard, don't wait until the next frame
to start the animation. Saves 16ms
- Scrims: Skip first frame, because it's completely black anyways.
Saves 16ms.
- Don't wait with navigation bar to show until the screen has turned
on. Window manager is blocked on DisplayPowerController anyways, so
the animation will exactly be started when the screen turns on. Fixes
some jank as well.
- Window manager: Don't wait for the window below Keyguard for draw
completion until turning on screen. Saves a lot of time depending on
how the app is behaving.

Bug: 23401557
Change-Id: I9734f9a12143f0e3c0647e9aa066831a29a6de63