The Tor Browser / file revision

 // If an array is truncated to the left of an iterator it, it.next() returns { done: true }.

 load(libdir + "asserts.js");

 load(libdir + "iteration.js");

 var arr = [0, 1, 2];

 var it = arr[std_iterator]();

 var ki = arr.keys();

 var ei = arr.entries();

 assertIteratorNext(it, 0);

 assertIteratorNext(it, 1);

 assertIteratorNext(ki, 0);

 assertIteratorNext(ki, 1);

 assertIteratorNext(ei, [0, 0]);

 assertIteratorNext(ei, [1, 1]);

 arr.length = 1;

 assertIteratorDone(it, undefined);

 assertIteratorDone(ki, undefined);

 assertIteratorDone(ei, undefined);