Fix bug 2995805 - splitMotionEvents behavior change

Changed the new split motion events behavior to match the enshrined
behavior. A return value of false from a target's dispatchTouchEvent
will not prevent the target from receiving further events in the
gesture unless it is the initial ACTION_DOWN event.

Change-Id: Ied8d531dfec7009a4124ed670b1700753c3f9caa