Extensions Docs Server: Fix headings with no IDs

chrome/common/extensions/docs/templates/articles/app_intents.html

 <h1>Connect Apps with Web Intents</h1>
 
 
 <p>
 <a href="http://webintents.org/">Web Intents</a>
 allow your application to quickly communicate
 with other applications on the user's system and inside their browser.
 Your application can register to handle specific user actions
 such as editing images via the <code>manifest.json</code>;
 your application can also invoke actions to be handled by other applications.
@@ skipping 180 matching lines @@
 <h2 id="errors">Handling Errors and Exceptions</h2>
 <p>
    If your service application needs to signal to the client application
    that an unrecoverable error has occurred,
    then your application will need
    to call <code>postError</code> on the intent object.
    This will signal to the client’s onError callback
    that something has gone wrong.
 </p>
 
-<h3>Client</h3>
+<h3 id="client">Client</h3>
 
 <pre>
 var intent = new WebKitIntent("http://webintents.org/edit", "image/png", "dataUri://");
 
 var onSuccess = function(data) {};
 var onError = function() {};
 
 window.navigator.webkitStartActivity(intent, onSuccess, onError);
 </pre>
 
-<h3>Service</h3>
+<h3 id="service">Service</h3>
 <pre>
 chrome.app.runtime.onLaunched(function(intent) {
   // App Launched
   console.log(intent.action);
   console.log(intent.type);
   var data = intent.data;
   // Do something with the data;
 
   intent.postResult(newData);
 });
 </pre>
 
-<p class="backtotop"><a href="#top">Back to top</a></p>
+<p class="backtotop"><a href="#top">Back to top</a></p>