diff -r 000000000000 -r 6474c204b198 services/sync/tps/extensions/mozmill/resource/modules/stack.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/sync/tps/extensions/mozmill/resource/modules/stack.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at http://mozilla.org/MPL/2.0/. */
+
+var EXPORTED_SYMBOLS = ['findCallerFrame'];
+
+
+/**
+ * @namespace Defines utility methods for handling stack frames
+ */
+
+/**
+ * Find the frame to use for logging the test result. If a start frame has
+ * been specified, we walk down the stack until a frame with the same filename
+ * as the start frame has been found. The next file in the stack will be the
+ * frame to use for logging the result.
+ *
+ * @memberOf stack
+ * @param {Object} [aStartFrame=Components.stack] Frame to start from walking up the stack.
+ * @returns {Object} Frame of the stack to use for logging the result.
+ */
+function findCallerFrame(aStartFrame) {
+  let frame = Components.stack;
+  let filename = frame.filename.replace(/(.*)-> /, "");
+
+  // If a start frame has been specified, walk up the stack until we have
+  // found the corresponding file
+  if (aStartFrame) {
+    filename = aStartFrame.filename.replace(/(.*)-> /, "");
+
+    while (frame.caller &&
+           frame.filename && (frame.filename.indexOf(filename) == -1)) {
+      frame = frame.caller;
+    }
+  }
+
+  // Walk even up more until the next file has been found
+  while (frame.caller &&
+         (!frame.filename || (frame.filename.indexOf(filename) != -1)))
+    frame = frame.caller;
+
+  return frame;
+}