Merge "Fix CellLayout cast exception when drag is canceled" into sc-dev am: 76f5572648 am: bf9d632680

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14948453

Change-Id: Ice942e1456e95271048d409903ff69e2b2ccb8b3