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 + "eqArrayHelper.js");

 load(libdir + "iteration.js");

 var g = newGlobal();

 var iterator_fn = Map.prototype[std_iterator];

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

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

 var mapw = g.eval("Map([['x', 1], ['y', 2]])");

 assertEqArray(iterator_fn.call(mapw).next().value, ["x", 1]);

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

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

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

 var iterw = mapw[std_iterator]();

 assertEqArray(next_fn.call(iterw).value, ["x", 1]);

 assertEqArray(next_fn.call(iterw).value, ["y", 2]);

 assertEq(next_fn.call(iterw).done, true);