[Fuchsia] Filter flaky webgl_conformance test on Fuchsia

Bug: 1130706
Change-Id: Iaf8bf9e37a06747d74c0722ce490e1dbd26ee9c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2504202
Auto-Submit: Chong Gu <chonggu@google.com>
Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Chong Gu <chonggu@google.com>
Cr-Commit-Position: refs/heads/master@{#822035}

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

@@ -245,6 +245,9 @@ crbug.com/1136414 [ fuchsia ] conformance/ogles/GL/fract/fract_001_to_006.html [
 crbug.com/1136414 [ fuchsia ] conformance/ogles/GL/build/build_009_to_016.html [ Skip ]
 crbug.com/1136414 [ fuchsia ] conformance/ogles/GL/mat/mat_009_to_016.html [ Skip ]
 
+# Anti-aliasing disabled on Fuchsia
+[ fuchsia ] conformance/context/context-attributes-alpha-depth-stencil-antialias.html [ Failure ]
+
 ####################
 # Win failures     #
 ####################