Remain the old hardware requirement for turning on clampArrayAccess. But
also turns it on universally for WebGL context. So that we won't suffer
from clampArrayAccess not handled properly on some compute shader deqp
tests.

Bug: chromium:1042252, angleproject:4361
Change-Id: Ib11affd6df27ce7d2100980d2b8decdee36876e8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2026029Reviewed-by: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Shrek Shao <shrekshao@google.com>