Make a copy of MotionEvent in MotionEventHelper.transform.

RotateLayout transforms the event in dispatchTouchEvent.
If the event is not handled, the parent of RotateLayout
may send the transformed event to other views and the
coordinates will be wrong. Make a copy of MotionEvent in
transform. This also makes the behavior consistent in
different API levels.

bug:6974916
Change-Id: Id835767cc9be3f244e5abe2b855e5188045adedc