diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/missingArgTest.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/missingArgTest.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+function arity1(x)
+{
+  return (x == undefined) ? 1 : 0;
+}
+function missingArgTest() {
+  var q;
+  for (var i = 0; i < 10; i++) {
+    q = arity1();
+  }
+  return q;
+}
+assertEq(missingArgTest(), 1);