parse valueless attributes (e.g. itemscope)

And allow nested tags, which was a newly encountered bug

test.html

@@ -39,5 +39,23 @@
       </a>
     </li>
   </ul>
+<section itemscope itemtype="http://schema.org/Person"> 
+  Hello, my name is 
+  <span itemprop="name">John Doe</span>,
+  I am a 
+  <span itemprop="jobTitle">graduate research assistant</span> 
+  at the 
+  <span itemprop="affiliation">University of Dreams</span>. 
+  My friends call me 
+  <span itemprop="additionalName">Johnny</span>. 
+  You can visit my homepage at 
+  <a href="http://www.JohnnyD.com" itemprop="url">www.JohnnyD.com</a>. 
+  <section itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
+    I live at 
+    <span itemprop="streetAddress">1234 Peach Drive</span>,
+    <span itemprop="addressLocality">Warner Robins</span>,
+    <span itemprop="addressRegion">Georgia</span>.
+  </section>
+</section>
 </body>
 </html>