Re-enable Mac Document/Window idlharness WPT

This reverts commit 0e528de2. The test
should be passing now that web platform tests has fully synced its IDL
with the HTML spec, and the -expected.txt files have been regenerated
with the latest Chrome implementation.

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

Bug: 1158672
Bug: 1157917
Change-Id: If3e717b05de26d26595c649979f52e5d3343ae62
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2593887Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Commit-Queue: Domenic Denicola <domenic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837250}

third_party/blink/web_tests/TestExpectations

@@ -5923,8 +5923,5 @@ crbug.com/1157861 http/tests/devtools/console/paintworklet-console-selector.js [
 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 ]
-
 # Sheriff 2020-12-14
 crbug.com/1046784 http/tests/devtools/console/console-context-selector.js [ Pass Timeout ]