Add a test for volatile aliases of the same shader image Bug: angleproject:3032 Bug: angleproject:7343 Bug: angleproject:7398 Change-Id: I6ea6abea0b9dafd93bc297499df23be27904c996 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3656314 Reviewed-by: Stephen White <senorblanco@chromium.org> Commit-Queue: Stephen White <senorblanco@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>