[REQUIRED] Describe your environment

• Operating System version: Ubuntu 17.10
• Firebase SDK version: 4.11.0
• Firebase Product: Auth

[REQUIRED] Describe the problem

Steps to reproduce:

If you try to use the Auth function createUserAndRetrieveDataWithEmailAndPassword, Typescript complaints about it: Property 'createUserAndRetrieveDataWithEmailAndPassword' does not exist on type 'Auth'.

Relevant Code:

In firebase/index.d.ts the function createUserAndRetrieveDataWithEmailAndPassword should be defined in the Auth interface, as it is in auth-types/index.d.ts.