[Sheriff] Update expectations for ext/wpt/h/d/interfaces.worker.html

external/wpt/html/dom/interfaces.worker.html is failing consistently.

Tbr: tkent@chromium.org
Bug: 929122
Change-Id: Ic11fbea14f6b0ce84cc3d34c93af6b33922ead32
Reviewed-on: https://chromium-review.googlesource.com/c/1456282Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Auto-Submit: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629577}

third_party/blink/web_tests/TestExpectations

@@ -6042,3 +6042,6 @@ crbug.com/927862 [ Win10 ] virtual/user-activation-v2/fast/events/no-blur-on-pag
 
 # Recently became flaky on multiple platforms (Linux and Windows primarily)
 crbug.com/927769 fast/webgl/OffscreenCanvas-webgl-preserveDrawingBuffer.html [ Skip ]
+
+# Sheriff 2019-02-06
+crbug.com/929122 external/wpt/html/dom/interfaces.worker.html [ Failure ]