Mark a WebGL2 test Flaky

deqp/functional/gles3/shaderoperator/common_functions.html
on Mac Intel.

BUG=820225
TBR=kbr@chromium.org

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: If8790e13fc6e1563d58aa7e03dadffdb6e23fa80
Reviewed-on: https://chromium-review.googlesource.com/956320
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541937}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -689,6 +689,8 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
         ['mac', 'no_passthrough', 'intel'], bug=679692)
     self.Fail('deqp/functional/gles3/fbomultisample*',
         ['mac', 'intel'], bug=641209)
+    self.Flaky('deqp/functional/gles3/shaderoperator/common_functions.html',
+        ['mac', 'intel'], bug=820225)
     self.Fail('deqp/functional/gles3/texturefiltering/2d_combinations_01.html',
         ['mac', 'intel'], bug=606074)
     self.Fail('deqp/functional/gles3/texturefiltering/' +