Suppress tex-2d-rgb16f-rgb-half_float on macOS.

conformance2/textures/canvas/tex-2d-rgb16f-rgb-half_float.html has
become flaky, reporting an error in SharedImageStub with subsequent
context loss.

Bug: 965209
Change-Id: I3e7e5e2f456d0bbf1b5f87cf5cc78511131e1083
Tbr: geofflang@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1620699
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661491}
1 file changed