diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug849730.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug849730.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,7 @@
+const Cu = Components.utils;
+
+function run_test() {
+  var sb = new Cu.Sandbox('http://www.example.com');
+  sb.arr = [3, 4];
+  do_check_true(Cu.evalInSandbox('Array.isArray(arr);', sb));
+}