title: firefox sandbox iframe location changing when it shouldn't
body: <p>When using html5 sandbox iframe I want the iframe to not be able to change its location:</p>
  
  <pre><code>&lt;iframe sandbox="allow-forms allow-popups allow-pointer-lock allow-same-origin allow-scripts" class="iframe visible" src="thesource.html" width="100%" scrolling="auto" frameborder="0"&gt;&lt;/iframe&gt;
  </code></pre>
  
  <p>It works great in Chrome but in Firefox an sandboxed iframe can still redirect.</p>
  
  <p>it's a <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=785310">known bug</a> but how can I patch it so that all Firefox users won't be redirected?</p>