Restore opaque alpha value when AlphaAnimation finishes

Restore opaque alpha value when AlphaAnimation finishes

Alpha values were being set correctly on native Display Lists during an
AlphaAnimation, but not when the animation finished. Only non-1 values
were being propagated to the Display List properties.

The fix is to track when we've set a non-1 alpha value from an AlphaAnimation
and to notice that flag when the value is 1 (because the animation ended), so that
we propagate that value correctly. Using the flag avoids sending a value of 1
(by far the most common case) unless we really need to restore it after animating
it with non-1 values.

Issue #6600592 Sometimes album art blends with list asset on queue

Change-Id: I51047d756a4ac42a2d907a4d77963cc23dfb1db3