code: private void addNthOfType() {
          for (Node node : nodes) {
              int count = 1;
              Node n = DOMHelper.getPreviousSiblingElement(node);
              while (n != null) {
                  if (DOMHelper.getNodeName(n).equals(DOMHelper.getNodeName(node))) {
                      count++;
                  }
                  
                  n = DOMHelper.getPreviousSiblingElement(n);
              }
              
              if (specifier.isMatch(count)) {
                  result.add(node);
              }
          }
      }
docs: Add {@code :nth-of-type} elements.
  
  @see <a href="http://www.w3.org/TR/css3-selectors/#nth-of-type-pseudo"><code>:nth-of-type</code> pseudo-class</a>