diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_bug641378.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_bug641378.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,46 @@
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+var timer;
+
+// This test XPConnect's ability to deal with a certain type of exception. In
+// particular, bug 641378 meant that if an exception had both 'message' and
+// 'result' properties, then it wouldn't successfully read the 'result' field
+// out of the exception (and sometimes crash).
+//
+// In order to make the test not fail completely on a negative result, we use
+// a timer. The first time through the timer, we throw our special exception.
+// Then, the second time through, we can test to see if XPConnect properly
+// dealt with our exception.
+var exception = {
+  message: "oops, something failed!",
+
+  tries: 0,
+  get result() {
+    ++this.tries;
+    return 3;
+  }
+};
+
+var callback = {
+  tries: 0,
+  notify: function (timer) {
+    if (++this.tries === 1)
+      throw exception;
+
+    try {
+        do_check_true(exception.tries >= 1);
+    } finally {
+        timer.cancel();
+        timer = null;
+        do_test_finished();
+    }
+  }
+};
+
+function run_test() {
+  do_test_pending();
+
+  timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+  timer.initWithCallback(callback, 0, timer.TYPE_REPEATING_SLACK);
+}