These were not output prior to this CL.  Of these qualifiers, readonly
and writeonly are unnecessary as ANGLE already does the appropriate
validation, but the rest (coherent, volatile, restrict) are necessary,
even though the tests pass on the bots by coincidence of driver
behavior/test simplicity.

Bug: angleproject:3602
Change-Id: Ie75fee0f004944b50ef21124ba25c4315e082b85
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1976499Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>