Run WebGL2 conformance tests on Mac with the passthrough command decoder.

Adds these tests to the chromium.gpu.fyi bots only, and not trybots yet,
due to lack of capacity.

BUG=982294

Change-Id: I3332c981c4102577aaf1d16af29b3cd351637bd3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1839031
Commit-Queue: Geoff Lang <[email protected]>
Reviewed-by: Kenneth Russell <[email protected]>
Reviewed-by: Yuly Novikov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#704870}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index d6c0fcc..610e3c5 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1722,6 +1722,9 @@
     'remove_from': [
       # Not enough capacity. https://crbug.com/946694
       'ANGLE GPU Win10 x64 Release (Intel HD 630)',
+      # Not enough capacity. https://crbug.com/982294
+      'Mac Pro FYI Release (AMD)',
+      'Mac FYI Retina Release (NVIDIA)',
     ],
   },
   'webgl2_conformance_tests': {