Fix pointer index out of range exception DO NOT MERGE

Avoid pointer index out of range error if return value is -1 of
findPointerIndex() when there is no data available for that pointer
identifier.

Change-Id: I2a08f04c678164e220852094baa124ba157e2e42
Signed-off-by: tingna_sung <tingna_sung@htc.com>

Fixes bug 18883936

services/core/java/com/android/server/wm/StackTapPointerEventListener.java

@@ -57,6 +57,7 @@ public class StackTapPointerEventListener implements PointerEventListener {
                 if (mPointerId >= 0) {
                     int index = motionEvent.findPointerIndex(mPointerId);
                     if ((motionEvent.getEventTime() - motionEvent.getDownTime()) > TAP_TIMEOUT_MSEC
+                            || index < 0
                             || (motionEvent.getX(index) - mDownX) > mMotionSlop
                             || (motionEvent.getY(index) - mDownY) > mMotionSlop) {
                         mPointerId = -1;