In the discussion in [881047](https://bugzilla.mozilla.org/show_bug.cgi?id=881047) and in the [promise.jsm docs](https://developer.mozilla.org/en-US/docs/Mozilla/JavaScript_code_modules/Promise.jsm) it mentions one can still use this -- also we have an open PR #1077 to make this loadable via `mozIJSSubScriptLoader`

I don't mind getting rid of this, but I'm not sure of the consensus outside of the SDK to be able to use this when wanting additional features (`promised` and `all` in this case)