freeze doesn't rewrite arity errors

[gfbee]

A small thing, from grepping the source for procedure-rename and case-lamba to see how they're handled if used to implement any of the api, since then one can't rely on rewriting : racket/racket#3234 racket/racket#3235 .

Language: Beginning Student; memory limit: 2000 MB.
> (require 2htdp/image) (freeze 1 2)
freeze: arity mismatch;
 the expected number of arguments does not match the given number
  given: 2
  arguments...:
   1
   2