base

Bring back some status bar animations.

Change Ie817b396 removed the layout transition from the main
status bar, fixing a number of weird bugs caused by the
translations on CHANGE_APPEARING and CHANGE_DISAPPEARING.

This change restores the layout transitions, but only the
alpha fade on APPEARING and DISAPPEARING. Doing this should
bring back the useful part of the status bar animations
(i.e. things fading in & out) without the buggy part (things
sliding around to make room for the things fading in & out).

Additionally, these fade-only layout transitions are now
properly applied to the clock/notification area (when
bringing up the notifications panel) and the icons within
the navigation cluster (so the legacy MENU key will fade
in).

Bug: 3503960
Bug: 3489129
Change-Id: I1ea433c41f2f930342ae2486505b0fee19709f9c