limited vectors with size: option break instance?

[cgay]

This assertion from the dylan-test-suite limited-is-limited test fails:

  let <integer-vector> = limited(<vector>, of: <integer>);
  let x = make(<integer-vector>, size: 10, fill: 10);
  //---*** sadly, the following fails due to limited-vector being ill-defined                                                                                                                                                               
  //       (look especially on the method in vector.dylan on of == <object>                                                                                                                                                                 
  //       and what happens if of == #f) - hannes (Jan 2012)                                                                                                                                                                                
  check-false("x is not instance of a vector with size 5",
              instance?(x, limited(<vector>, size: 5)));