implement getBufferSubDataAsync prototype

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

 # Copyright (c) 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 from gpu_tests.webgl_conformance_expectations import WebGLConformanceExpectations
 
 # See the GpuTestExpectations class for documentation.
 
 class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
   def __init__(self, conformance_path, url_prefixes=None):
     super(WebGL2ConformanceExpectations, self).__init__(
@@ skipping 37 matching lines @@
     self.Fail('deqp/functional/gles3/framebufferblit/conversion_28.html',
         ['mac'], bug=654187)
     self.Fail('deqp/functional/gles3/framebufferblit/conversion_30.html',
         ['mac'], bug=654187)
     self.Fail('deqp/functional/gles3/framebufferblit/conversion_31.html',
         ['mac'], bug=654187)
     self.Fail('deqp/functional/gles3/framebufferblit/conversion_33.html',
         ['mac'], bug=654187)
 
     # All platforms.
+    self.Fail('conformance2/context/methods-2.html', bug=616554)
     self.Flaky('conformance2/query/occlusion-query.html', bug=603168)
 
     # Windows only.
     # We are awesome!
     self.Fail('conformance2/buffers/getBufferSubData.html',
         ['win'], bug=654201)
 
     # Win / NVidia
     self.Flaky('deqp/functional/gles3/fbomultisample*',
         ['win', 'nvidia'], bug=631317)
@@ skipping 820 matching lines @@
     # self.Fail(page_name,
     #     ['linux', ('nvidia', 0x1), 'debug', 'opengl'])
     # self.Fail(page_name,
     #     ['win', ('nvidia', 0x1), 'debug', 'opengl'])
 
     # Conflicts if between a generic os condition and a specific version
     # self.Fail(page_name,
     #     ['xp', ('nvidia', 0x1), 'debug', 'opengl'])
     # self.Fail(page_name,
     #     ['win', ('nvidia', 0x1), 'debug', 'opengl'])