code: function contains(container, maybe) {
    // 16 is for a nodeType constant: window.Node.DOCUMENT_POSITION_CONTAINED_BY,
    // but the window.Node object is not available in IE8
    return container.contains ? container.contains(maybe) :
      !!(container.compareDocumentPosition(maybe) & 16);
  }
docs: Fallback contains check from http://stackoverflow.com/a/6131052
  @param  {Element} container Container element
  @param  {Element} maybe     Element that may be within container
  @return {Boolean}           Whether container contains maybe