base

Isolate layout and animation wallpaper objects.

Provide separate copies of mWallpaperTarget, mWallpaperTokens, and
mLower/UpperWallpaperTarget in the layout and animation sides of
Window Manager.

Simplify constructors of WindowAnimator and WindowStateAnimator.

Change-Id: I7e35794a432c25c4194c046e9e27150d1c905403