Performs a shallow copy on this hash.
@return {Ext.util.HashMap} The new hash object.
function() {
        var hash = new this.self(this.initialConfig),
            map = this.map,
            key;

        hash.suspendEvents();
        for (key in map) {
            if (map.hasOwnProperty(key)) {
                hash.add(key, map[key]);
            }
        }
        hash.resumeEvents();
        return hash;
    }