diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/auto-regress/bug643847.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/auto-regress/bug643847.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+// Binary: cache/js-dbg-64-c811be25eaad-linux
+// Flags:
+//
+function f(o) {
+  o.constructor = function() {};
+}
+__proto__.__defineSetter__('constructor',
+function(v) {});
+f({});
+Object.defineProperty(__proto__, 'constructor', {
+  writable: true,
+});
+f({});