Fix lockscreen launch animations

- Fix the case in WindowAnimator where the real window was ready
to draw while the starting window was playing the unlock animation.
- Always delay Keyguard done when clicking on a notification. Some
notifications started services/broadcasts instead and thus we didn't
wait, making it a jarring transition. In case the notification click
doesn't result in an activity start at all, we still have the timeout
that saves us from freezing (3s), but most notifications should start
an activity.

Bug: 19412725
Change-Id: I78f6839f59986f8f7ecdff70227d5690a504f475