diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testLetOverridingArgs.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testLetOverridingArgs.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,5 @@
+function f1() { let (arguments = 42) { return arguments } }
+assertEq(f1(), 42);
+
+function f2() { let (arguments) { return arguments } }
+assertEq(f2(), undefined);