Prevent a crash when touching the stack while it's flinging out of the dismiss area.

Fixes: 133867082
Test: atest SystemUITests
Change-Id: Id9a9eb85eeb53002a23f62605b21beafe1c4338f

packages/SystemUI/src/com/android/systemui/bubbles/animation/StackAnimationController.java

@@ -271,6 +271,8 @@ public class StackAnimationController extends
                 },
                 DynamicAnimation.TRANSLATION_X, DynamicAnimation.TRANSLATION_Y);
 
+        // If we're flinging now, there's no more touch event to catch up to.
+        mFirstBubbleSpringingToTouch = false;
         mIsMovingFromFlinging = true;
         return destinationRelativeX;
     }