This test case simulates a slow network, and starts a web worker thread to write a log message when retrieving media metadata to see if the webkit thread is blocked by media retrieving thread.
This test case is for https://bugs.webkit.org/show_bug.cgi?id=80978

EXPECTED (video.error == 'null') OK
Message from worker thread OK
EVENT(loadedmetadata)
loaded metadata of media file OK
END OF TEST