title: What is the source of the double-dollar sign selector query function in Chrome/Firefox?
body: <p>Check <a href="http://jsfiddle.net/T2PMc/">this jsfiddle</a>, and have a look at the console. <code>$$</code> is not defined. Now, open a completely new window, and enter <code>$$</code> into a console. It defines a function for getting a (jquery-like) array of all the dom elements which match the selector:</p>
  
  <p><code>&gt; $$</code></p>
  
  <pre class="lang-js prettyprint-override"><code>bound: function () {
    return document.querySelectorAll.apply(document, arguments)
  }
  </code></pre>
  
  <p>Is this being added by Dev tools? It is also present when using Firebug in Firefox. Is it used internally by the tools themselves?</p>