Merge "Use alpha instead of invisible for views below shelf to skip redraw" into sc-dev am: 27a1fdb018 am: 202ca05bd6 am: 0af5f37c16

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

Change-Id: I40d4f281224ef1d7422ee571815f73e666e6d424