diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug646968-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug646968-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,7 @@
+var x = 5;
+let (x = x)
+    assertEq(x, 5);
+let (x = eval("x"))
+    assertEq(x, 5);
+let (x = function () { with ({}) return x; })
+    assertEq(x(), 5);