diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/regress/regress-573875.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/regress/regress-573875.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,21 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+var o = {__iterator__:null, a:1, b:2, c:3}
+var expect = '__iterator__,a,b,c,';
+var actual = '';
+
+try {
+    for (var i in o)
+        actual += i + ',';
+} catch (e) {
+    actual = '' + e;
+    if (/invalid __iterator__ value/.test(actual) ||
+        /null is not a function/.test(actual)) {
+        expect = actual;
+    }
+}
+
+reportCompare(expect, actual, "ok");