[Sheriff] Mark virtual/video-surface-layer/media/autoplay-muted.html as flaky timeout

Bug: 935595
Change-Id: Idd3a7a67120fd25bb05869d7be034275e5785c6b
NoTry: True
Tbr: xiaochengh@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/1487091Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635155}

third_party/blink/web_tests/TestExpectations

@@ -6024,6 +6024,7 @@ crbug.com/935027 http/tests/devtools/animation/animation-transition-setTiming-cr
 
 # Sheriff 2019-02-25
 crbug.com/935587 [ Mac ] virtual/video-surface-layer/media/stable/video-object-fit-stable.html [ Failure Pass ]
+crbug.com/935595 virtual/video-surface-layer/media/autoplay-muted.html [ Timeout Pass ]
 
 # Device Sensor Events are being restricted to secure browsing contexts, but the change is still gated on a runtime flag.
 crbug.com/932078 http/tests/security/powerfulFeatureRestrictions/device-orientation-future-behavior-on-insecure-origin.html [ Skip ]