[Sheriff] Disable...

[Sheriff] Disable external/wpt/focus/iframe-activeelement-after-focusing-out-iframes.html on Win and Mac

It is flaky.

Bug: 1168522
Change-Id: Idcc7293410a65f3f41d172b31d486789b0004bcf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640333
Commit-Queue: Gabriel Charette <gab@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Christos Froussios <cfroussios@chromium.org>
Auto-Submit: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845313}

third_party/blink/web_tests/TestExpectations

@@ -5950,6 +5950,9 @@ crbug.com/1167309 fast/canvas/canvas-createImageBitmap-drawImage.html [ Pass Fai
 
 crbug.com/1168373 [ Debug ] http/tests/devtools/layers/layers-3d-view-hit-testing.js [ Failure ]
 
+# Sheriff 2021-01-20
+crbug.com/1168522 external/wpt/focus/iframe-activeelement-after-focusing-out-iframes.html [ Pass Failure ]
+
 # DevTools roll
 crbug.com/1050549 http/tests/devtools/network/preview-searchable.js [ Pass Failure ]
 crbug.com/1050549 http/tests/devtools/console/console-correct-suggestions.js [ Pass Failure ]