Further suppress conformance/textures/misc/texture-sub-image-cube-maps.html

Also flaky in Release and on Win10.

TBR=kbr

Bug: 772037
Change-Id: I6108376212d131c9972a47f3232614674b94beac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2348696Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796888}

content/test/gpu/gpu_tests/test_expectations/webgl_conformance_expectations.txt

@@ -146,7 +146,7 @@ crbug.com/1105129 [ win ] conformance/context/context-creation.html [ RetryOnFai
 
 # Win / AMD / Passthrough command decoder / D3D11
 crbug.com/685232 [ win amd d3d11 passthrough ] conformance/textures/misc/copytexsubimage2d-subrects.html [ RetryOnFailure ]
-crbug.com/772037 [ win7 debug amd d3d11 passthrough ] conformance/textures/misc/texture-sub-image-cube-maps.html [ RetryOnFailure ]
+crbug.com/772037 [ win amd d3d11 passthrough ] conformance/textures/misc/texture-sub-image-cube-maps.html [ RetryOnFailure ]
 crbug.com/772037 [ win7 release amd d3d11 passthrough ] conformance/extensions/oes-texture-half-float.html [ RetryOnFailure ]
 
 # Vulkan / Passthrough command decoder