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if (!Element.prototype.matches)
    Element.prototype.matches = Element.prototype.msMatchesSelector ||
                                Element.prototype.webkitMatchesSelector;

if (!Element.prototype.closest)
    Element.prototype.closest = function(s) {
        var el = this;
        if (!document.documentElement.contains(el)) return null;
        do {
            if (el.matches(s)) return el;
            el = el.parentElement;
        } while (el !== null);
        return null;
    };

if (window.Element && !Element.prototype.closest) {
    Element.prototype.closest =
    function(s) {
        var matches = (this.document || this.ownerDocument).querySelectorAll(s),
            i,
            el = this;
        do {
            i = matches.length;
            while (--i >= 0 && matches.item(i) !== el) {};
        } while ((i < 0) && (el = el.parentElement));
        return el;
    };
}