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

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

Change-Id: I8013e795feae00201b73c0a0d254a69fd8289e8f