title: firebase Facebook oAuth addScope()
body: <p>I am using firebase with angular and oAuth with the firebase facebook provider. Everything is working fine.
  However, when I am trying to add a new scope (user_friends) for examples I don't get any data (the popup asks me for the correct scopes): </p>
  
  <pre><code>//auth.service.ts
   signInWithFacebook() {
      const provider =  new firebase.auth.FacebookAuthProvider();
      provider.addScope("user_friends");
      return this.oAuthLogin(provider);
   }
   private oAuthLogin(provider) {
      return this._firebaseAuth.auth.signInWithPopup(provider)
      .then((credential) =&gt; {
         this.updateUserData(credential.user)
      })
   }
  </code></pre>
  
  <p>So the credential got basic userInformation (displayName, photoUrl) as usual.
  I tried to look for the returned Promise as a callback :</p>
  
  <pre><code>type UserCredential = {
     additionalUserInfo?: firebase.auth.AdditionalUserInfo | null;
     credential: firebase.auth.AuthCredential | null;
     operationType?: string | null;
     user: firebase.User | null;
  };
  </code></pre>
  
  <p>We can see that there is a firebase.user getting alot of method but no adding string for my new scope.</p>
  
  <pre><code>interface UserInfo {
      displayName: string | null;
      email: string | null;
      phoneNumber: string | null;
      photoURL: string | null;
      providerId: string;
      uid: string;
  }
  </code></pre>
  
  <p>Thus I dont see how my user_friends data, which is an array (below) can be added to the credentials data (which method?) and displayed in my console.</p>
  
  <pre><code>"friends": {
    "data": [
      //friends id and their name
    ],
  
    "summary": {
      "total_count": 631
    }
  }
  </code></pre>
  
  <p>thanks for your help !</p>