Changes

=== Won't this limit experimentation ? ===As is, it will. We are trying to devise a system that will allow for extension authors to have the flexibility to implement features that the WebExtension API doesn't currently allow. We will post more information about that when there is something solid [https://discourse.mozilla-community.org/t/proposal-native-js-to share-embrace-extend-the-webextensions-api/3457 Some discussion] has already begun. The intent is for add-on authors to experiment through this mechanism with the knowledge that there are no guarantees of compatibility between Firefox releases and use that to inform future additions to the WebExtension API