[Sheriff] Added test as flaky in all platforms

Bug: 1019662,1019663
Change-Id: Ib9af219a8e386954260d10db852da1761b2366ac
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890074Reviewed-by: Kamila Hasanbega <hkamila@chromium.org>
Commit-Queue: Kamila Hasanbega <hkamila@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710787}

third_party/blink/web_tests/TestExpectations

@@ -5744,6 +5744,7 @@ crbug.com/1018064 [ Mac10.13 ] virtual/threaded/http/tests/devtools/tracing/time
 # Sheriff 2019-10-30
 crbug.com/1018027 virtual/threaded-no-composited-antialiasing/animations/custom-properties/registered-var-to-registered.html [ Pass Crash ]
 crbug.com/1014810 [ Mac ] virtual/threaded/external/wpt/animation-worklet/stateful-animator.https.html [ Pass Timeout ]
+crbug.com/1019662 external/wpt/html/dom/idlharness.worker.html [ Pass Timeout ]
 crbug.com/1019663 external/wpt/web-nfc/NDEFReader_options.https.html [ Failure Pass ]
 
 # Temporarily disabled for landing coverage changes in DevTools