Some ES drivers also generate INVALID_ENUM errors when querying this
format, particuarly on linux Mesa+nouveau.

BUG=angleproject:2219

Change-Id: I7b9cf9b003a0125fabdda63038b4c8941710e1db
Reviewed-on: https://chromium-review.googlesource.com/754329Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>