Bug 842762: Uplift Add-on SDK changeset bf2c2f609babcea412a2349a431ae6bdbedcf05d

https://github.com/mozilla/addon-sdk/compare/4e44dd094e8636216e8c9ca5664866a5cf7d0cdd...bf2c2f609babcea412a2349a431ae6bdbedcf05d