Fix check for whether stencil write is masked out The stencil write mask is the only thing that decides what bits get written to. Previously, this was masked with the reference bitmask to determine if any bits get written to, which is incorrect. The effect of this was that the Vulkan backend would use the READ_ONLY layout for the depth/stencil attachment even though stencil could have been written to the attachment. Bug: angleproject:42266334 Change-Id: Ice6a35f4691fc8e09c7d5e1db6439c3079dfa039 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5887905 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com> Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>