It's kinda broken, but at least it's creating arrays of the right sizes and not crashing <_<

results.txt

STRICT MODE
[]
[3,32767]
[2]


SLOPPY 'FAST' MODE
[]
[3,32767]
[2]


SLOPPY 'SLOW' MODE
[2]
[4,32767,null]
[3,32767]

v8-rest-params.js

(function() {
  "use strict";

  function fn(a, ...b) {
    return b;
  }

  print("STRICT MODE");
  print(JSON.stringify(fn(1)));
  print(JSON.stringify(fn(1, 2, 3)));
  print(JSON.stringify(fn(1, 2)));
  print("\n");
})();

(function() {
  function fn(a, ...b) {
    return b;
  }

  print("SLOPPY 'FAST' MODE");
  print(JSON.stringify(fn(1)));
  print(JSON.stringify(fn(1, 2, 3)));
  print(JSON.stringify(fn(1, 2)));
  print("\n");
})();

(function() {
  function fn(a, a, ...b) {
    return b;
  }

  print("SLOPPY 'SLOW' MODE");
  print(JSON.stringify(fn(1, 1)));
  print(JSON.stringify(fn(1, 1, 2, 3)));
  print(JSON.stringify(fn(1, 1, 2)));
  print("\n");
})();