The clamping doesn't happen on NVIDIA so this is a test that will
confirm a follow-up compiler workaround patch works properly.

BUG=angleproject:2299

Change-Id: I006b522d014e29d2a5e634dfb9cf827ee3bc0536
Reviewed-on: https://chromium-review.googlesource.com/852252
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>