Reduce usage of webkit prefixes in extension examples

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

 <meta name="doc-family" content="apps">
 <h1>Build Apps with AngularJS</h1>
 <!--Article written by Eric Bidelman-->
 <p>
 This guide gets you started building Chrome Apps
 with the <a href="http://angularjs.org/">AngularJS</a> MVC framework.
 To illustrate Angular in action,
 we'll be referencing an actual app built using the framework,
 the Google Drive Uploader.
 The <a href="https://github.com/GoogleChrome/chrome-app-samples/tree/master/samples/gdrive">source code</a>
@@ skipping 169 matching lines @@
 &lt;style>
 nav:hover #close-button {
   opacity: 1;
 }
 
 #close-button {
   float: right;
   padding: 0 5px 2px 5px;
   font-weight: bold;
   opacity: 0;
-  -webkit-transition: all 0.3s ease-in-out;
+  transition: all 0.3s ease-in-out;
 }
 &lt;/style>
 </pre>
 <pre data-filename="main.html">
 &lt;button class="btn" id="close-button" title="Close">x&lt;/button>
 </pre>
 
 <p>
 In
 <a href="https://github.com/GoogleChrome/chrome-app-samples/blob/master/samples/gdrive/js/app.js">app.js</a>,
@@ skipping 549 matching lines @@
         $scope.fetchDocs();
       });
     });
   });
 
   return gdocs;
 });
 </pre>
 
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