diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/truthiness/not.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/truthiness/not.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,24 @@
+function t1(v)
+{
+  if (!v)
+    return 1;
+  return 0;
+}
+
+assertEq(t1(objectEmulatingUndefined()), 1);
+assertEq(t1(objectEmulatingUndefined()), 1);
+assertEq(t1(objectEmulatingUndefined()), 1);
+
+function t2(v)
+{
+  if (!v)
+    return 1;
+  return 0;
+}
+
+assertEq(t2(17), 0);
+assertEq(t2(0), 1);
+assertEq(t2(-0), 1);
+assertEq(t2(objectEmulatingUndefined()), 1);
+assertEq(t2(objectEmulatingUndefined()), 1);
+assertEq(t2(objectEmulatingUndefined()), 1);