This prevents an error in case ANGLE is run on an older Vulkan driver
that does not support the VK_KHR_maintenance1 extension.

Bug: angleproject:3035
Change-Id: I7e2b74bcb88bffdfc2a525a1d332eb3ef7d23d7c
Reviewed-on: https://chromium-review.googlesource.com/c/1387347Reviewed-by: Ian Elliott <ianelliott@google.com>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Ian Elliott <ianelliott@google.com>