[Command buffer]: Don't blit color buffer if draw buffers have no image during blitting

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 30 matching lines @@
     self.Skip('deqp/functional/gles3/builtinprecision/*.html', bug=619403)
 
     # All platforms.
     self.Flaky('conformance2/query/occlusion-query.html', bug=603168)
     self.Fail('conformance2/glsl3/tricky-loop-conditions.html', bug=483282)
 
     self.Fail('conformance2/rendering/depth-stencil-feedback-loop.html',
         bug=660844) # WebGL 2.0.1
     self.Fail('conformance2/rendering/rendering-sampling-feedback-loop.html',
         bug=660844) # WebGL 2.0.1
-    self.Fail('conformance2/rendering/read-draw-when-missing-image.html',
-        ['linux', 'nvidia', 'opengl'], bug=672719) # WebGL 2.0.1
     self.Fail('conformance2/textures/misc/' +
         'integer-cubemap-specification-order-bug.html',
         bug=483282) # owner:cwallez, test might be buggy
 
     # Windows only.
     self.Fail('conformance2/rendering/blitframebuffer-outside-readbuffer.html',
         ['win'], bug=644740)
 
     # Win / NVidia
     self.Flaky('deqp/functional/gles3/fbomultisample*',
@@ skipping 793 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'])