Clear transform when updating animation frame

This is a common step to support general animation.
Otherwise postTranslate will keep accumulating offset that causes the
content to be outside of screen.

The default embedded animation doesn't have problem because it
is lucky that contains setTranslate. While a pure alpha animation
doesn't contain setTranslate.

Fix: 308898792
Test: Open Settings with embedded activity enabled.
      Click Display -> Brightness level and click Storage on left.
      It will perform the alpha animation correctly which
      is specified by the activity of "Brightness level".
Change-Id: I3575dd0c0e6797b38b67825b978afebe0fafff3e