diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug646968-5.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug646968-5.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+var y = 7;
+
+switch (function () { with ({}) return y; }()) {
+case 7:
+    let y;
+    break;
+default:
+    throw 'FAIL';
+}