suppress the webgl2 conformance test to prevent bot failure

BUG=672719, 675819
CQ_INCLUDE_TRYBOTS=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;master.tryserver.chromium.android:android_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2590103002
Cr-Commit-Position: refs/heads/master@{#439720}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -583,6 +583,8 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
     # Linux Intel with ANGLE only
     self.Fail('deqp/functional/gles3/framebufferblit/conversion_07.html',
         ['linux', 'intel', 'opengl'], bug=598902)
+    self.Fail('conformance2/rendering/read-draw-when-missing-image.html',
+        ['linux', 'intel', 'opengl'], bug=672719) # WebGL 2.0.1
 
     # Linux AMD only.
     # It looks like AMD shader compiler rejects many valid ES3 semantics.