diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testBug703857.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testBug703857.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+Function.prototype.X = 42;
+function ownProperties() {
+    var props = {};
+    var r = function () {};
+    for (var a in r) {
+        let (a = function() { for (var r=0;r<6;++r) ++a; }) {
+            a();
+        }
+        props[a] = true;
+    }
+}
+ownProperties();