BUG=angleproject:2756
TEST=angle_end2end_tests.ComputeShaderTest.SamplingAndImageReadWrite/ES3_1_D3D11

Change-Id: I8f112227c5703fcaafffbd2262e6a039f869c483
Reviewed-on: https://chromium-review.googlesource.com/1161754
Commit-Queue: Xinghua Cao <xinghua.cao@intel.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>