Test playing video in a detached document

Many tests don't insert the media element into a document and this
doesn't seem to be a problem. However, Opera 20 (Blink), Safari 7
(WebKit) and Firefox 30 (Gecko) fail this test. Opera 12.16 (Presto)
passes it, but only after playing to the end; it seems like timeupdate
events aren't being fired correctly. IE was not tested.