<ol>
<li>Create a new tab.</li>
<li>Navigate that tab to about:blank.</li>
<li>Paste the following into the location bar:
  <pre>javascript:x = new XMLHttpRequest(); x.open('get', 'http://jquery.com', false); x.send(); alert(x.responseText)</pre>
</li>
<li>Press "Enter".</li>
<li>If you see the contents of jquery.com appear in an alert dialog, something
has gone wrong.</li>
</ol>