Bookmarklet to uncripple Kindle Cloud Reader

gistfile1.js

(function() {
  function uncrippleFrame() {
    var body = this.contentWindow.document.getElementsByTagName('body')[0];

    this.contentWindow.onclick = null;
    body._frame = this;

    body.onmousemove = function() {
      this._frame.contentWindow.onclick = null;
      this.setAttribute('style', '-webkit-user-select: auto;');
      this.oncontextmenu = body.onselectstart = null;
    };
    body.onmousemove();
  };

  var container = document.getElementsByTagName('iframe')[0].contentWindow;
  var frames = container.document.getElementsByTagName('iframe');

  for (var i = 0; i < frames.length; i++) {
    uncrippleFrame.call(frames[i]);
    frames[i].onload = uncrippleFrame;
  }
})();

i'm pretty new at this. downloaded the file, but can't get it to open in any of my browsers (tried IE and firefox). any suggestions?

Just tried it with Safari 5.1.4 on my Mac and it doesn't work at all. No errors in the dev console either.