Vulkan: Fix missing visibility barrier for host-visible buffer writes See https://chromium-review.googlesource.com/c/angle/angle/+/1661252 for context. This was accidentally broken during the command graph rework. This will eventually be validated by syncval. See https://github.com/KhronosGroup/Vulkan-ValidationLayers/issues/2329. Bug: angleproject:5070 Change-Id: Ic16fa900e554d46e54b42fc3fbe0f96d5327fa0f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2689379 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>