replace flaky DCHECK in DrawingBuffer with early-out

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

 # Copyright (c) 2013 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.
 import os
 
 from gpu_tests.gpu_test_expectations import GpuTestExpectations
 
 # See the GpuTestExpectations class for documentation.
 
 class WebGLConformanceExpectations(GpuTestExpectations):
@@ skipping 352 matching lines @@
 
     # Mac AMD failures
     self.Fail('conformance/glsl/bugs/bool-type-cast-bug-int-float.html',
         ['mac', 'amd'], bug=483282)
     self.Fail('conformance/extensions/webgl-draw-buffers.html',
         ['mac', 'amd'], bug=625365)
     self.Fail('conformance/rendering/clipping-wide-points.html',
         ['mac', 'amd'], bug=642822)
 
     # Mac Intel failures
-    self.Flaky('conformance/textures/webgl_canvas/tex-' +
-               '2d-rgb-rgb-unsigned_byte.html',
-               ['mac', 'intel'], bug=648377)
 
     # Mac Retina NVidia failures
     self.Fail('conformance/attribs/gl-disabled-vertex-attrib.html',
         ['mac', ('nvidia', 0xfe9)], bug=635081)
     self.Fail('conformance/programs/' +
         'gl-bind-attrib-location-long-names-test.html',
         ['mac', ('nvidia', 0xfe9)], bug=635081)
     self.Fail('conformance/programs/gl-bind-attrib-location-test.html',
         ['mac', ('nvidia', 0xfe9)], bug=635081)
     self.Fail('conformance/renderbuffers/framebuffer-object-attachment.html',
@@ skipping 464 matching lines @@
     self.Fail('conformance/textures/misc/texture-npot.html',
         ['chromeos', ('intel', 0xa011)], bug=375554)
     self.Fail('conformance/textures/misc/texture-npot-video.html',
         ['chromeos', ('intel', 0xa011)], bug=375554)
     self.Fail('conformance/textures/misc/texture-size.html',
         ['chromeos', ('intel', 0xa011)], bug=375554)
     self.Fail('conformance/uniforms/gl-uniform-arrays.html',
         ['chromeos', ('intel', 0xa011)], bug=375554)
     self.Skip('conformance/uniforms/uniform-default-values.html',
         ['chromeos', ('intel', 0xa011)], bug=375554)