Use the correct parent size to initialize animations

The original logic would use out-of-date parent sizes to initialize
animations. If the screen size is changed after assigning mAnimDw and
mAnimDh in the constructor of WindowStateAnimator, the fromDeltaY
(in the most cases) of TranslateAnimation would be initialized
incorrectly.

In this change, we always use up-to-date parent sizes to initialize
animations to prevent the issue.

https://code.google.com/p/android/issues/detail?id=170348

Change-Id: Ib9c609121228934bdb463263feb1924eb389c1d2