diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_5/extensions/regress-480579.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_5/extensions/regress-480579.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor: Jason Orendorff
+ */
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 480579;
+var summary = 'Do not assert: pobj_ == obj2';
+var actual = '';
+var expect = '';
+
+
+//-----------------------------------------------------------------------------
+test();
+//-----------------------------------------------------------------------------
+
+function test()
+{
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+
+  expect = '12';
+
+  a = {x: 1};
+  b = {__proto__: a};
+  c = {__proto__: b};
+  for (i = 0; i < 2; i++) {
+    print(actual += c.x);
+    b.x = 2;
+  }
+
+  reportCompare(expect, actual, summary);
+
+  exitFunc ('test');
+}