diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/extensions/regress-636697.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/extensions/regress-636697.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+var a = {set p(x) {}};
+a.watch('p', function () {});
+var b = Object.create(a);
+b.watch('p', function () {});
+delete b.p;
+b.p = 0;
+
+reportCompare(0, 0, 'ok');