pixel tests: Reenable Pixel_OffscreenCanvasAccelerated2D*

crrev.com/c/1099564 disabled the Pixel_OffscreenCanvasAccelerated2D*
tests, correctly increasing the version in pixel_test_pages.py.
These tests seem to be passing according to [1], so let's try
and reenable them.

[1] http://chromium-browser-gpu-tests.commondatastorage.googleapis.com/view_test_results.html?868948046954e7d06d97eb10544ea3b27b320953_android_marshmallow_arm64_rel_telemetry

CQ-DEPEND=CL:1303097

Bug: 805031
Change-Id: Ie6b48fde0a03fefbbff185de1818e3105192f5f3
Reviewed-on: https://chromium-review.googlesource.com/c/1303097Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603959}

content/test/gpu/gpu_tests/pixel_expectations.py

@@ -16,10 +16,6 @@ class PixelExpectations(GpuTestExpectations):
     self.Flaky('Pixel_GpuRasterization_BlueBox',
         ['win', ('amd', 0x6613)], bug=653538)
 
-    # TODO(senorblanco) generate new reference images after Edge-AA tess change.
-    self.Fail('Pixel_OffscreenCanvasAccelerated2D')
-    self.Fail('Pixel_OffscreenCanvasAccelerated2DWorker')
-
     # Software compositing is not supported on Android: we skip the tests that
     # disable GPU compositing (--disable-gpu-compositing).
     self.Skip('Pixel_OffscreenCanvasUnaccelerated2D', ['android'])