Suppress a Flaky WebGL2 test

deqp/functional/gles3/transformfeedback/random_separate_points.html
on Mac Retina Nvidia

TBR=kbr@chromium.org

Bug: 857112
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I260fe3a05bf4f68cd9cb154e9a265fe58eada288
Reviewed-on: https://chromium-review.googlesource.com/1117037Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570896}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -558,6 +558,10 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
         'texsubimage3d_pbo_3d_01.html',
         ['mac', ('nvidia', 0xfe9)], bug=614174)
 
+    self.Flaky('deqp/functional/gles3/transformfeedback/' +
+        'random_separate_points.html',
+        ['mac', ('nvidia', 0xfe9)], bug=857112)
+
     self.Fail('deqp/functional/gles3/fragmentoutput/array.fixed.html',
         ['mac', ('nvidia', 0xfe9)], bug=483282)
     self.Fail('deqp/functional/gles3/fragmentoutput/basic.fixed.html',