title: Cross Domain request withCredentials not working in Firefox
body: <p>I'm building an Backbone.js app to talk to an api that I've also built. </p>
  
  <p>The api sits on 
      api.foo.com
  website on 
      web.foo.com</p>
  
  <p>Im managed to get CORS working with the appropriate header fields in apache</p>
  
  <pre><code>Header set Access-Control-Allow-Origin "http://web.foo.com"
  Header set Access-Control-Allow-Methods "GET,PUT,POST,DELETE,OPTIONS"
  Header set Access-Control-Allow-Headers Content-Type
  Header set Access-Control-Allow-Credentials "true"
  Header append Access-Control-Allow-Headers Origin
  Header append Access-Control-Allow-Headers Accept
  Header append Access-Control-Allow-Headers X-Requested-With
  </code></pre>
  
  <p>and setting the xhrFields to</p>
  
  <pre><code>    f = { withCredentials: true}
  
      params.xhrFields = f;
  
      // Make the request, allowing the user to override any Ajax options.
      $.ajax(params);
  </code></pre>
  
  <p>this all works with chrome. Im about to do a post to api.foo.com/sessions login, get a cookie and then do another request to api.foo.com with that cookie.</p>
  
  <p>Unfortunately when I switched to firefox 10.0.7, this didnt work. The withCredentials didnt seem to get jquery to pick up the cookie and use it.</p>
  
  <p>Unlike most the questions relating to this on stackoverflow, this is not a one off, I need to get this to work consistently across browsers (I havent even got to IE yet).</p>
  
  <p>Im using </p>
  
  <p>Backbone.js 0.9.1
  jquery 1.7.1
  require 1.0.7
  underscore 1.3.1</p>
  
  <p>Works on </p>
  
  <p>Chrome 17.0.963.65</p>
  
  <p>doesnt work on firefox 10.0.2</p>
  
  <p>Can anybody help me?</p>