Mozilla GitHub Repo?

Does anyone else think the developer experience of writing code for Mozilla would be greatly simplified if there was a GitHub Repository for all the code? New programmers could especially be aided by this, for Mercurial and Mozilla Build are new software that should be learned, whereas GitHub usage is easy to learn.

I apologize if there is already a GitHub repo that contains the code and can be committed to - I did not do as deep a search as I could have.