diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug845201.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug845201.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,18 @@
+function sbTest() {
+  var threw = false;
+  try {
+    for (var x in Components) { }
+    do_check_true(false, "Shouldn't be able to enumerate Components");
+  } catch(e) {
+    do_check_true(true, "Threw appropriately");
+    threw = true;
+  }
+  do_check_true(threw, "Shouldn't have thrown uncatchable exception");
+}
+
+function run_test() {
+  var sb = Components.utils.Sandbox('http://www.example.com', { wantComponents: true });
+  sb.do_check_true = do_check_true;
+  Components.utils.evalInSandbox(sbTest.toSource(), sb);
+  Components.utils.evalInSandbox('sbTest();', sb);
+}