Mark http/tests/inspector-protocol/service-worker/service-worker-fetch-async-stacks.js timeout

Bug: 1136690
Change-Id: Icefa36ff77c21cb49e3ff65120e9a91ad679dec0
Tbr: nhiroki@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462758Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815462}

third_party/blink/web_tests/LeakExpectations

@@ -172,6 +172,9 @@ crbug.com/1068175 [ Linux ] external/wpt/referrer-policy/gen/worker-module.http-
 # a prior crash.
 crbug.com/1103082 [ Linux ] fast/forms/select/select-change-layout-object-crash.html [ Failure ]
 
+# Sheriff 2020-10-08
+crbug.com/1136690 [ Linux ] http/tests/inspector-protocol/service-worker/service-worker-fetch-async-stacks.js [ Pass Timeout ]
+
 ###########################################################################
 # WARNING: Memory leaks must be fixed asap. Sheriff is expected to revert #
 # culprit CLs instead of suppressing the leaks. If you have any question, #