The Tor Browser / file revision

 // map.iterator() and iter.next() are non-generic but work on cross-compartment wrappers.

 load(libdir + "asserts.js");

 load(libdir + "iteration.js");

 var g = newGlobal();

 var iterator_fn = Set.prototype[std_iterator];

 assertThrowsInstanceOf(function () { iterator_fn.call({}); }, TypeError);

 assertThrowsInstanceOf(function () { iterator_fn.call(Map()); }, TypeError);

 var setw = g.eval("Set(['x', 'y'])");

 assertIteratorNext(iterator_fn.call(setw), "x");

 var next_fn = Set()[std_iterator]().next;

 assertThrowsInstanceOf(function () { next_fn.call({}); }, TypeError);

 assertThrowsInstanceOf(function () { next_fn.call(Map()[std_iterator]()); }, TypeError);

 var iterw = setw[std_iterator]();

 assertIteratorResult(next_fn.call(iterw), "x", false);

 assertIteratorResult(next_fn.call(iterw), "y", false);

 assertIteratorResult(next_fn.call(iterw), undefined, true);