diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Set-iterator-add-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Set-iterator-add-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+// set.iterator() is live: entries added during iteration are visited.
+
+var set = Set([5]);
+var log = '';
+for (let x of set) {
+    log += x + ';';
+    if (x > 0)
+        set.add(x - 1);
+}
+assertEq(log, '5;4;3;2;1;0;');
+assertEq(set.size, 6);