title: PHP block is not parsed in html
body: <p>I am writing the following html code:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"&gt;
  &lt;head&gt;
   &lt;meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /&gt; 
  
  &lt;script type="text/javascript"&gt;
      function detectBrowser(){
          if(navigator.appName === "Microsoft Internet Explorer"){
              window.open("redirect.html", "_parent");
          }
      }
  &lt;/script&gt;
  &lt;/head&gt;
  
  &lt;body onload="detectBrowser()"&gt;
  &lt;div class="mainBody"&gt;  
  &lt;?php
      echo "test";
  ?&gt;
  &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>But the php block doesn't display test for me. It looks like it is not parsed and I can see the php code in the webpage's source. Any one can tell the problem? <br>Thank you</p>