[j0hnik]

или вот этот код в начало скрипта.

(function(ELEMENT) {
	ELEMENT.matches = ELEMENT.matches || ELEMENT.mozMatchesSelector || ELEMENT.msMatchesSelector || ELEMENT.oMatchesSelector || ELEMENT.webkitMatchesSelector;
	ELEMENT.closest = ELEMENT.closest || function closest(selector) {
		if (!this) return null;
		if (this.matches(selector)) return this;
		if (!this.parentElement) {return null}
			else return this.parentElement.closest(selector)
		};
}(Element.prototype));