Merge "Additional null-checks for animations in case child views are removed...

Merge "Additional null-checks for animations in case child views are removed at an inopportune time." into rvc-dev am: 6d4caab6 am: 570bf65e am: 867475ad

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11990653

Change-Id: Iac6033e00e1223dcb9f83a0dca9c64dbd58b781d