diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/extensions/regress-604781-2.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/extensions/regress-604781-2.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+var log;
+function watcher(id, old, newval) { log += 'watcher'; return newval; }
+var o = { set x(v) { log += 'setter'; } };
+o.watch('x', watcher);
+Object.defineProperty(o, 'x', {value: 3, writable: true});
+log = '';
+o.x = 3;
+assertEq(log, 'watcher');
+
+reportCompare(0, 0, 'ok');