diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug711404.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug711404.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+function run_test()
+{
+  var p = Cc["@mozilla.org/hash-property-bag;1"].
+          createInstance(Ci.nsIWritablePropertyBag2);
+  p.setPropertyAsInt64("a", -4000);
+  do_check_neq(p.getPropertyAsUint64("a"), -4000);
+}