Vulkan: Enable EXT_frag_depth Natively supported with GLES3 dEQP tests already enabled and passing. Bug: angleproject:3218 Change-Id: I5ff94e3b16d2025a58d5a448383049f9330dd46f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1600864 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>