Other than for a Qualcomm driver bug workaround, this makes a few
fallbacks unnecessary.

Bug: angleproject:2361
Change-Id: I8bdc8efba69527ca89bfa7b646a9d41e07f4f895
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1541669Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>