imported/w3c/web-platform-tests/navigation-timing/nav2_test_attributes_values.html is flaky since r278477: https://results.webkit.org/?suite=layout-tests&test=imported%2Fw3c%2Fweb-platform-tests%2Fnavigation-timing%2Fnav2_test_attributes_values.html
Alex marked it as flaky in http://trac.webkit.org/changeset/278704/webkit since this was giving out false positives on EWS.
<rdar://problem/79143327>