function removeEvent(node, event, fn, opt_useCapture) {
    if (typeof node.removeEventListener == 'function') {
      node.removeEventListener(event, fn, opt_useCapture || false)
    } else if (typeof node.detatchEvent == 'function') {
      node.detatchEvent('on' + event, fn)
    }
  }
Removes a previously added event handler from a DOM node.
@param {Node} node The DOM node to remove the event handler from.
@param {string} event The event name.
@param {Function} fn The event handler to remove.
@param {boolean} opt_useCapture If the event handler was added with this
    flag set to true, it should be set to true here in order to remove it.