The following layout test is flaky on debug WK2 bots. imported/w3c/web-platform-tests/streams/readable-streams/general.serviceworker.https.html Probable cause: Unknown, the diff shows that this is a harness timeout. The test takes between 1-29 seconds to run, most seem to hover around 10s. Flakiness Dashboard: https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=imported%2Fw3c%2Fweb-platform-tests%2Fstreams%2Freadable-streams%2Fgeneral.serviceworker.https.html