Add back classes and object literals to staging

On V8 4.1, both are back to the staged area.

public/es6.html

@@ -89,6 +89,8 @@ <h2 class="faq-title">
       </h2>
       <div class="faq-body">
         <ul class="task-list">
+          <li><a href="https://github.com/lukehoban/es6features#classes">Classes</a> (strict mode only)</li>
+          <li><a href="https://github.com/lukehoban/es6features#enhanced-object-literals">Object literal extensions</a></li>
           <li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol"><code>Symbol.toStringTag</code></a> (user-definable results for <code>Object.prototype.toString</code>)</li>
         </ul>
       </div>