The Tor Browser / file revision

 // Removing many Set entries does not cause a live iterator to skip any of the

 // entries that were not removed. (Compacting a Set must not be observable to

 // script.)

 load(libdir + "iteration.js");

 var set = Set();

 for (var i = 0; i < 32; i++)

     set.add(i);

 var iter = set[std_iterator]();

 assertIteratorNext(iter, 0);

 for (var i = 0; i < 30; i++)

     set.delete(i);

 assertEq(set.size, 2);

 for (var i = 32; i < 100; i++)

     set.add(i);  // eventually triggers compaction

 for (var i = 30; i < 100; i++)

     assertIteratorNext(iter, i);

 assertIteratorDone(iter, undefined);