Fix NPE when TaskView isn't attached to RecentsView

Test: theoretical
Fixes: 201481275
Change-Id: Ie10b5ebac373e41a4d4113ee3cda737d88adad8a
diff --git a/quickstep/src/com/android/quickstep/views/TaskMenuView.java b/quickstep/src/com/android/quickstep/views/TaskMenuView.java
index 03ab737..5c73fbb 100644
--- a/quickstep/src/com/android/quickstep/views/TaskMenuView.java
+++ b/quickstep/src/com/android/quickstep/views/TaskMenuView.java
@@ -210,7 +210,7 @@
 
     @Override
     public void onScrollChanged() {
-        RecentsView rv = mTaskView.getRecentsView();
+        RecentsView rv = mActivity.getOverviewPanel();
         setPosition(mTaskView.getX() - rv.getScrollX(), mTaskView.getY() - rv.getScrollY(),
                 rv.getOverScrollShift());
     }