1. DomName('Document.createElementNS')
  2. DocsEditable()
Element createElementNS(String namespaceURI, String qualifiedName, [ String typeExtension ])

Source 

@DomName('Document.createElementNS')
@DocsEditable()
Element createElementNS(String namespaceURI, String qualifiedName, [String typeExtension]) {
  return (typeExtension == null) ?
    _blink.BlinkDocument.instance.createElementNS_Callback_2_(this, namespaceURI, qualifiedName) :
    _blink.BlinkDocument.instance.createElementNS_Callback_3_(this, namespaceURI, qualifiedName, typeExtension);
}