def ng_binding(binding, opt = {})
    opt[:root_selector] ||= ng_root_selector
    row = ng.row(opt)
    ng_bindings(binding, opt)[row]
  end
def ng_binding(binding, opt = {})
    opt[:root_selector] ||= ng_root_selector
    row = ng.row(opt)
    ng_bindings(binding, opt)[row]
  end
Node for nth binding match

 @param opt
 - :row
 - :exact
 - :root_selector
 - :wait
 @return nth node