diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Map-iterator-add-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Map-iterator-add-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,15 @@
+// map.iterator() is live: entries added during iteration are visited.
+
+var map = Map();
+function force(k) {
+    if (!map.has(k) && k >= 0)
+        map.set(k, k - 1);
+}
+force(5);
+var log = '';
+for (let [k, v] of map) {
+    log += k + ';';
+    force(v);
+}
+assertEq(log, '5;4;3;2;1;0;');
+assertEq(map.size, 6);