Update selector-css2.js

Corrected YUI's buggy implementation of getElementsByTagName (useful on agents who don't support getEBTN or QSA on document fragments).

    YUI().use("node", "selector-css2", function (Y) {
        // we want to set this to false in order to simulate browsers 
        // who don't support getEBTN or QSA on fragments
        Y.Selector.useNative = false;
        
        var fragment = Y.one(Y.config.doc.createDocumentFragment());
        
        // ES5 required
        fragment.setHTML(
            "<div> \
                <div> \
                    <div></div> \
                </div> \
                <div></div> \
            </div>");
        
        // should return 4 elements, but doesn't
        Y.log(Y.one(fragment).all("*").size());
    });