Bug 924565 - Part 1: Declare nsIObserver QI in DOMRequestHelper child classes. r=fabrice, a=koi+
Bug 924565 - Part 2: Use weak observer reference for DOMRequestHelper. r=fabrice, a=koi+
Bug 924565 - Part 3: Add tests verifying DOMRequestHelper cleanup and weak ref behavior. r=fabrice, a=koi+