diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Set-iterator-remove-4.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Set-iterator-remove-4.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,31 @@
+// Multiple live iterators on the same Set can cope with removing entries.
+
+load(libdir + "iteration.js");
+
+// Make a set.
+var set = Set();
+var SIZE = 7;
+for (var j = 0; j < SIZE; j++)
+    set.add(j);
+
+// Make lots of iterators pointing to entry 2 of the set.
+var NITERS = 5;
+var iters = [];
+for (var i = 0; i < NITERS; i++) {
+    var iter = set[std_iterator]();
+    assertIteratorNext(iter, 0);
+    assertIteratorNext(iter, 1);
+    iters[i] = iter;
+}
+
+// Remove half of the set entries.
+for (var j = 0; j < SIZE; j += 2)
+    set.delete(j);
+
+// Make sure all the iterators still work.
+for (var i = 0; i < NITERS; i++) {
+    var iter = iters[i];
+    for (var j = 3; j < SIZE; j += 2)
+        assertIteratorNext(iter, j);
+    assertIteratorDone(iter, undefined);
+}