diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug778409.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug778409.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,11 @@
+function run_test() {
+  var Cu = Components.utils;
+  var sb1 = Cu.Sandbox('http://example.com');
+  var sb2 = Cu.Sandbox('http://example.org');
+  var chromeObj = {foo: 2};
+  var sb1obj = Cu.evalInSandbox('new Object()', sb1);
+  chromeObj.__proto__ = sb1obj;
+  sb2.wrapMe = chromeObj;
+  do_check_true(true, "Didn't crash");
+  do_check_eq(sb2.wrapMe.__proto__, sb1obj, 'proto set correctly');
+}