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

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

Change-Id: Ie703fdd8884320d7c21878ad43943cac0392a8b0