I was not able to test it so far, but I think this code will work:
Code:
//      Generate the data rows from the data in the Store
        var treeAsArray = new Array();
        this.store.getRootNode().cascadeBy(
            function(node){
                if (node.get('id') !== 'root') treeAsArray.push(node);
            },
            this
        );        
        
        for (var i = 0, it = treeAsArray, l = it.length; i < l; i++) {
...