diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/for-of/array-iterator-shrinking.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/for-of/array-iterator-shrinking.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+// 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);