Update test expectations for test with frequent timeouts.

Bug: 1046784
Change-Id: I2779fd3a8ac092ab7f4cb69b77ae44740f3ab8f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2645204
Commit-Queue: Katie Dektar <katie@chromium.org>
Auto-Submit: Katie Dektar <katie@chromium.org>
Reviewed-by: Nina Satragno <nsatragno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846304}

third_party/blink/web_tests/TestExpectations

@@ -5703,7 +5703,8 @@ crbug.com/1150475 fast/dom/open-and-close-by-DOM.html [ Pass Failure ]
 
 #Sheriff 2020-11-23
 crbug.com/1152088 [ Mac10.13 Debug ] fast/dom/cssTarget-crash.html [ Pass Timeout ]
-crbug.com/1149734 http/tests/devtools/sources/source-frame-toolbar-items.js [ Pass Failure ]
+# Sheriff 2021-01-22 added Timeout per crbug.com/1046784:
+crbug.com/1149734 http/tests/devtools/sources/source-frame-toolbar-items.js [ Pass Failure Timeout ]
 crbug.com/1149734 http/tests/devtools/sources/debugger-frameworks/frameworks-sourcemap.js [ Pass Failure ]
 crbug.com/1149734 http/tests/devtools/sources/debugger-ui/continue-to-location-markers.js [ Pass Failure ]
 crbug.com/1149734 http/tests/devtools/sources/debugger-ui/inline-scope-variables.js [ Pass Failure ]