Merge "Use alpha instead of invisible for views below shelf to skip redraw" into sc-dev am: 27a1fdb018 am: 34644987c6 am: d64e6ed07a

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15331191

Change-Id: Id2aa23e3d09136947e3f5f97b5c7272de3b24071