Remove failure expectations for two WebGL extension tests.

oes-standard-derivatives.html and ext-frag-depth.html are now fixed with
the recent expando-loss fix.

BUG=540916
TBR=zmo@chromium.org

Review URL: https://codereview.chromium.org/1403053003

Cr-Commit-Position: refs/heads/master@{#353944}

content/test/gpu/gpu_tests/webgl_conformance_expectations.py

@@ -38,10 +38,6 @@ class WebGLConformanceExpectations(GpuTestExpectations):
         bug=478572)
     self.Fail('conformance/extensions/ext-sRGB.html',
         bug=540900)
-    self.Fail('conformance/extensions/oes-standard-derivatives.html',
-        bug=5400916)
-    self.Fail('conformance/extensions/ext-frag-depth.html',
-        bug=5400916)
 
     # Win failures
     self.Fail('conformance/glsl/bugs/' +