As Facebook is going to deprecate graph API 2.3 version at 10 July.
The package supporting account-facebook is: facebook-oauth: https://github.com/meteor/meteor/tree/master/packages/facebook-oauth
The code in this package (here) uses a URL of the form:
https://www.facebook.com/v2.2/dialog/oauth?client_id=...
Does that answer your question? (I don’t know whether the v2.2 URL for OAuth is going to be deprecated or removed).
The page: https://developers.facebook.com/docs/apps/changelog suggests that v2.2/{object} was due to expire on March 25, 2017.