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

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

Change-Id: Ia4259df3fc6e6288cc4edd56db306d4f73c51e17