Enable external/wpt/workers/opaque-origin.html

There haven't been any crashes or timeouts in a long time, only normal failures:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_layout_tests&tests=%2Fworkers%2Fopaque-origin.html

See web-platform-tests/wpt#11188.

Change-Id: I933124b8c406fd202a7d382350cfe259d6607d79
Reviewed-on: https://chromium-review.googlesource.com/1140053
Commit-Queue: Robert Ma <robertma@chromium.org>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575647}

third_party/WebKit/LayoutTests/TestExpectations

@@ -3462,7 +3462,6 @@ crbug.com/666993 [ Win ] external/wpt/requestidlecallback/callback-idle-periods.
 # Crashes with DCHECK enabled, but not on normal Release builds.
 crbug.com/809935 external/wpt/css/css-fonts/variations/font-style-interpolation.html [ Timeout ]
 crbug.com/626703 external/wpt/css/css-ui/text-overflow-011.html [ Failure Crash Pass ]
-crbug.com/626703 external/wpt/workers/opaque-origin.html [ Failure Crash Timeout ]
 crbug.com/626703 external/wpt/html/rendering/non-replaced-elements/margin-collapsing-quirks/multicol-quirks-mode.html [ Pass Crash ]
 crbug.com/626703 external/wpt/html/rendering/non-replaced-elements/margin-collapsing-quirks/multicol-standards-mode.html [ Pass Crash Failure ]
 crbug.com/762017 external/wpt/html/semantics/embedded-content/media-elements/video_loop_base.html [ Pass Crash ]

third_party/WebKit/LayoutTests/external/wpt/workers/opaque-origin-expected.txt

@@ -0,0 +1,9 @@
+This is a testharness.js-based test.
+PASS Worker has an opaque origin.
+PASS Worker can read its own blobs.
+PASS Worker can read its owners blobs.
+FAIL Worker can XHR fetch a blob. assert_equals: expected "from page" but got ""
+FAIL Worker can fetch a blob. promise_test: Unhandled rejection with value: object "TypeError: Failed to fetch"
+FAIL Worker can access BroadcastChannel Failed to construct 'BroadcastChannel': Can't create BroadcastChannel in an opaque origin
+Harness: the test ran to completion.
+