diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/deepForInLoop.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/deepForInLoop.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+function deepForInLoop() {
+  // NB: the number of props set in C is arefully tuned to match 8 = 2.
+  function C(){this.p = 1, this.q = 2}
+  C.prototype = {p:1, q:2, r:3, s:4, t:5};
+  var o = new C;
+  var j = 0;
+  var a = [];
+  for (var i in o)
+    a[j++] = i;
+  return a.join("");
+}
+assertEq(deepForInLoop(), "pqrst");