diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/regress/regress-500528.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/regress/regress-500528.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,22 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor: Jason Orendorff
+ */
+
+// This test appeared in bug 497789 comment 78.
+
+var a = {x: 'a'},
+    b1 = Object.create(a),
+    c1 = Object.create(b1),
+    b2 = Object.create(a),
+    c2 = Object.create(b2);
+
+b2.x = 'b';  // foreshadowing a.x
+
+var s = '';
+for each (var obj in [c1, c2])
+    s += obj.x;
+assertEq(s, 'ab');
+
+reportCompare(0, 0, "Property cache soundness: objects with the same shape but different prototypes.");