diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/truthiness/if-equal-undefined.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/truthiness/if-equal-undefined.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,46 @@
+var counterF = 0;
+
+function f(v, value)
+{
+  if (v == undefined)
+    counterF++;
+  assertEq(counterF, value,
+           "failed: " + v + " " + value);
+}
+
+f({}, 0);
+f({}, 0);
+f(null, 1);
+f(null, 2);
+f(undefined, 3);
+f(undefined, 4);
+f(objectEmulatingUndefined(), 5);
+f(objectEmulatingUndefined(), 6);
+f(Object.prototype, 6);
+f(Object.prototype, 6);
+
+var counterG = 0;
+
+function g(v, value)
+{
+  if (v == undefined)
+    counterG++;
+  assertEq(counterG, value,
+           "failed: " + v + " " + value);
+}
+
+g({}, 0);
+g({}, 0);
+
+var counterH = 0;
+
+function h(v, value)
+{
+  if (v == undefined)
+    counterH++;
+  assertEq(counterH, value,
+           "failed: " + v + " " + value);
+}
+
+h(objectEmulatingUndefined(), 1);
+h(objectEmulatingUndefined(), 2);