code: private void addRootElement() {
  		Node root = helper.getRoot();
  		if (root != null)
  			result.add(root);
  	}
docs: Add the {@code :root} element.
  
  @see <a href="http://www.w3.org/TR/css3-selectors/#root-pseudo"><code>:root</code> pseudo-class</a>