num duration

Source 

@DomName('MediaSource.duration')
@DocsEditable()
num get duration => _blink.BlinkMediaSource.instance.duration_Getter_(this);
void duration=(num value)

Source 

@DomName('MediaSource.duration')
@DocsEditable()
set duration(num value) =>
    _blink.BlinkMediaSource.instance.duration_Setter_(this, value);