code: function removeDelegatedListener(el, type, listener) {
    var delegate = getDelegateFunction_(listener);
    decrementListenerCount(listener);
    if (getListenerCount(listener) <= 0) {
      delegateFunctionMap.delete(listener);
    }
    return el.removeEventListener(type, delegate);
  }
docs: Removes an event listener to an element where the event target
  is discovered by moving up the clicked element's descendants.
  @param {Element} el Element to host the listener.
  @param {string} type Listener type.
  @param {Function} listener Listener function.