Get nested namespace by property.

@private
function(root, action) {
        var parts, ns, i, l;
        
        root  = root || Ext.global;
        parts = action.toString().split('.');

        for (i = 0, l = parts.length; i < l; i++) {
            ns   = parts[i];
            root = root[ns];

            if (typeof root === 'undefined') {
                return root;
            }
        }

        return root;
    }