This eliminates a potential invalid access that would turn up in the Vulkan back-end. Also init a couple uninitialized variables. Should fix an ASSERT in the Vulkan back-end when running WebGL tests. Bug: chromium:1085627 Change-Id: I153f8dd83f567345b964b68784940d11712e7804 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2212498 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
