diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug942390.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug942390.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+var count = 0;
+Object.defineProperty(__proto__, "__iterator__", {
+    get: (function() {
+	count++;
+    })
+})
+__proto__ = (function(){})
+for (var m = 0; m < 7; ++m) {
+    for (var a in 6) {}
+}
+assertEq(count, 7);