Mark one WebGL2 test Flaky

conformance2/transform_feedback/too-small-buffers.html
on Win NVIDIA OpenGL no_passthrough

BUG=832238
TBR=kbr@chromium.org

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: Ie44d23e20053e06e7c355b2b20609a37b3d049ba
Reviewed-on: https://chromium-review.googlesource.com/1011597
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550510}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -229,6 +229,8 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
         ['win', 'nvidia', 'opengl'], bug=828572)
     self.Skip('conformance2/rendering/blitframebuffer-size-overflow.html',
         ['win', 'nvidia', 'opengl'], bug=830046)
+    self.Flaky('conformance2/transform_feedback/too-small-buffers.html',
+        ['win', 'nvidia', 'opengl', 'no_passthrough'], bug=832238)
 
     self.Flaky('deqp/functional/gles3/transformfeedback/*',
         ['win', ('nvidia', 0x1cb3), 'opengl'], bug=822733)