diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/ion/bug678239-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/ion/bug678239-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,7 @@
+function f(x, y, z) {
+    if (1)
+        x = z;
+    return x + y;
+}
+
+assertEq(f(0, 2, {}), "[object Object]2")