diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug639128.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug639128.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+function f(o) { 
+    Object.seal(o); 
+}
+gc();
+if(2 != 2) {
+    g = new f(g);
+}
+with({}) {
+    f({});
+}