The Tor Browser / file revision

 // If an array with an active iterator is lengthened, the iterator visits the new elements.

 load(libdir + "asserts.js");

 load(libdir + "iteration.js");

 var arr = [0, 1];

 var it = arr[std_iterator]();

 var ki = arr.keys();

 var ei = arr.entries();

 assertIteratorNext(it, 0);

 assertIteratorNext(ki, 0);

 assertIteratorNext(ei, [0, 0]);

 assertIteratorNext(it, 1);

 assertIteratorNext(ki, 1);

 assertIteratorNext(ei, [1, 1]);

 arr[2] = 2;

 arr.length = 4;

 assertIteratorNext(it, 2);

 assertIteratorNext(ki, 2);

 assertIteratorNext(ei, [2, 2]);

 assertIteratorNext(it, undefined);

 assertIteratorNext(ki, 3);

 assertIteratorNext(ei, [3, undefined]);

 assertIteratorDone(it, undefined);

 assertIteratorDone(ki, undefined);

 assertIteratorDone(ei, undefined);