This test seems flaky across many chromium testers and appears to have been flaky since it landed, alternating between passing and timing out: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=media%2Ftrack%2Ftrack-active-cues.html
This test doesn't seem to exist anymore.
Removing this in - https://github.com/WebKit/WebKit/pull/24695 Nothing to do here.