Mark external/wpt/css/filter-effects/idlharness.any.worker.html as flaky

The non-worker version is also flaky.

TBR=fs@opera.com

Bug: 1042453
Change-Id: I1109cd338dcb06a5cf457418dcc6b2fe6def13ef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2013499
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733826}

third_party/blink/web_tests/TestExpectations

@@ -373,6 +373,8 @@ crbug.com/997202 [ Win ] external/wpt/css/css-images/image-orientation/image-ori
 
 crbug.com/1042453 [ Win ] external/wpt/css/filter-effects/idlharness.any.html [ Timeout Pass ]
 crbug.com/1042453 [ Mac ] external/wpt/css/filter-effects/idlharness.any.html [ Timeout Pass ]
+crbug.com/1042453 [ Win ] external/wpt/css/filter-effects/idlharness.any.worker.html [ Timeout Pass ]
+crbug.com/1042453 [ Mac ] external/wpt/css/filter-effects/idlharness.any.worker.html [ Timeout Pass ]
 
 crbug.com/1042783 external/wpt/css/css-backgrounds/background-size/background-size-near-zero-png.html [ Failure ]
 crbug.com/1042783 external/wpt/css/css-backgrounds/background-size/background-size-near-zero-svg.html [ Failure ]