title: CORS withCredentials - support limited?
body: <p>I've noticed that certain browsers do not seem to support withCredentials in CORS requests, at least under some conditions. Specifically, in IE 10, attempting to set <code>xhr.withCredentials = true</code> results in:</p>
  
  <p><code>SCRIPT5022: InvalidStateError</code></p>
  
  <p>and in Safari 5 (but not 6) I get</p>
  
  <p><code>INVALID_STATE_ERR: DOM Exception 11: An attempt was made to use an object that is not, or is no longer, usable.</code></p>
  
  <p>again, in response to the same statement.</p>
  
  <p>Are these known problems, or am I setting up my XHR wrong somehow? Is there a list of which browsers support <code>withCredentials</code>?</p>