
PASS TextTrackCue should throw "TypeError" if the cue node is not a documentFragment 
PASS TextTrackCue should throw "InvalidNodeTypeError" if passed an invalid documentFragment 
PASS TextTrackCue should throw "InvalidNodeTypeError" if documentFragment has an invalid node 
PASS TextTrackCue should throw "InvalidStateError" if documentFragment doesn't have 'cuebackground' and 'cue' nodes 
PASS TextTrackCue should allow all valid node types 
PASS Test TextTrackCue.getCueAsHTML()