Ensure that transitions animating alpha end on a reasonable value

The Fade transition sets an initial alpha value of 0 when items are
appearing. This makes items invisible to start with, and then they
eventually fade in as part of the transition when the transition's
animation runs.

But if that animation/transition gets interrupted, or not started, then
the alpha value would not be restored, and the value would stay 0,
making the items invisible indefinitely. This is what was happening in
the action bar of the People app when performing a search.

The fix is to handle Transition and animation events to restore the alpha
to its true value when the transition completes, whether that
transition is canceled or not.

Issue #10726905 ActionBar weirdness in People app

Change-Id: Idb65fd8d471d2ac0a1ddc243fee00ae99f7e72d8