class Opal::Rewriters::JsReservedWords

def on_restarg(node)

def m(*); end
because it may have no name
Restarg is a special case 
def on_restarg(node)
  name, _ = *node
  if name
    node = node.updated(nil, [fix_var_name(name)], meta: {arg_name: name})
  end
  node
end