Remove suppressions for two AMD D3D9 tests.

The sRGB and depth texture tests should now pass on D3D9 AMD
systems. AMD-D3D9 only appears on the GPU FYI bots so GPU trybots
won't test this path.

BUG=angle:839

Review URL: https://codereview.chromium.org/792863002

Cr-Commit-Position: refs/heads/master@{#307961}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -61,10 +61,6 @@ class WebGLConformanceExpectations(GpuTestExpectations):
         ['win7', 'intel', 'nvidia'], bug=373972)
 
     # Win / AMD failures
-    self.Fail('conformance/extensions/ext-sRGB.html',
-        ['win', 'amd'], bug=839) # angle bug ID
-    self.Fail('conformance/extensions/webgl-depth-texture.html',
-        ['win', 'amd'], bug=839) # angle bug ID
     self.Fail('conformance/textures/texparameter-test.html',
         ['win', 'amd', 'd3d9'], bug=839) # angle bug ID