Sheriff: Fix Mac WPT

TBR: domenic
Bug: 1158672, 1157917
Change-Id: Ie10cad8aa48f989a8fd76eda0ed3e605b09fafb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2592228Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836992}

third_party/blink/web_tests/TestExpectations

@@ -5916,3 +5916,6 @@ crbug.com/1157861 http/tests/devtools/console/paintworklet-console-selector.js [
 # Wpt importer Sheriff 2020-12-11
 crbug.com/626703 [ Linux ] wpt_internal/storage/estimate-usage-details-filesystem.https.tentative.any.html [ Pass Failure ]
 crbug.com/626703 [ Mac ] external/wpt/mediacapture-image/MediaStreamTrack-getConstraints.https.html [ Pass Failure ]
+
+# WPT importer Sheriff 2020-12-14
+crbug.com/1158672 [ Mac ] external/wpt/html/dom/idlharness.https.html?include=(Document|Window) [ Pass Failure ]