Disable async-callstack-fetch.js

TBR: dgozman@chromium.org
No-Try: true
Bug: 936479
Change-Id: I57919f0358c30575a980377534a06b4e8ecf0760
Reviewed-on: https://chromium-review.googlesource.com/c/1492174Reviewed-by: Ella Ge <eirage@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636077}

third_party/blink/web_tests/TestExpectations

@@ -5890,6 +5890,7 @@ crbug.com/936108 virtual/streams-native/http/tests/streams/transferable/readable
 
 # Sheriff 2019-02-27
 crbug.com/936279 external/wpt/import-maps/fallback-disallowed.sub.tentative.html [ Failure Pass ]
+crbug.com/936479 [ Mac10.13 ] http/tests/devtools/sources/debugger/async-callstack-fetch.js [ Failure Pass ]
 
 # Device Sensor Events were restricted to secure browsing contexts in M74, with a flag available until M76 to undo the change in case of an emergency.
 crbug.com/932078 http/tests/security/powerfulFeatureRestrictions/device-orientation-on-insecure-origin.html [ Skip ]