diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Set-iterator-remove-5.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Set-iterator-remove-5.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,22 @@
+// Removing a Set entry already visited by an iterator does not cause any
+// entries to be skipped.
+
+var str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
+var set = Set(str);
+
+var log = '';
+var i = 0;
+for (var x of set) {
+    log += x;
+    if (i++ % 5 === 0) {
+        // Delete all entries preceding this one.
+        for (let y of set) {
+            if (y === x)
+                break;
+            set.delete(y);
+        }
+    }
+}
+assertEq(log, str);
+assertEq(set.size, 1);  // Elements 0 to 24 are removed, leaving only 25 (Z).
+assertEq(set.has('Z'), true);