Translator: Consolidate EvqFragDepth and EvqFragDepthEXT They were the same thing. Fixes SPIR-V generation which only handled EvqFragDepth. Bug: angleproject:4889 Change-Id: Id2c35f4c5a26e43ad16a420cc0306756a1add082 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3059922 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>