Revert "Disable angle-stuck-depth-textures flaky test entirely"

This reverts commit c34306d8.

Reason for revert: Win10 driver version was fixed

Original change's description:
> Disable angle-stuck-depth-textures flaky test entirely
> 
> Bug: 820419
> Tbr: kbr@chromium.org
> Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
> Change-Id: Ibd95ec218a700b7a9a6e34336f4ddee5442f8b02
> Reviewed-on: https://chromium-review.googlesource.com/956116
> Reviewed-by: Kenneth Russell <kbr@chromium.org>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>
> Commit-Queue: Luc Ferron <lucferron@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#542209}

TBR=jmadill@chromium.org,kbr@chromium.org,lucferron@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 820419
Change-Id: I3b86e2249440b195353583348b0c1fae010e3965
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/973981Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544832}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -246,8 +246,6 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
     # Win / Intel
     self.Fail('conformance/rendering/rendering-stencil-large-viewport.html',
         ['win', 'intel', 'd3d11'], bug=782317)
-    self.Fail('conformance2/textures/misc/angle-stuck-depth-textures.html',
-        ['win', 'intel', 'd3d11'], bug=820419)
 
     # Seems to cause the harness to fail immediately afterward
     self.Skip('conformance2/textures/video/tex-2d-rgba16f-rgba-half_float.html',