diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testBug566556.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testBug566556.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+var msg = "";
+try {
+    this.__defineSetter__('x', Object.create);
+    this.watch('x', function() {});
+    x = 3;
+} catch (e) {
+    msg = e.toString();
+}
+assertEq(msg, "TypeError: undefined is not an object or null");