title: firebase.auth(...).signInWithEmailAndPassword is not a function in Cloud Function
body: <p>I m getting Error while invoked function.
  I m using LsignInWithEmailAndPassword Method.Any Special Configuration is Require?</p>
  
  <pre><code>const functions = require('firebase-functions');
      const firebase=require('firebase-admin');
      firebase.initializeApp(functions.config().firebase);
  
  
       exports.login = functions.https.onRequest((request, response) =&gt; {
  
  
                 var data = {
        email    : 'demo@gmail.com',
        password : 'demo123'
      };
      var auth = null;
      firebase
        .auth()
        .signInWithEmailAndPassword(data.email, data.password)
        .then( function(user){
          response.send("Authenticated successfully with payload");
        //  console.log("Authenticated successfully with payload:", user);
          auth = user;
        })
        .catch(function(error){
          response.send("Login Failed!");
        //  console.log("Login Failed!", error);
        });
              //  response.send("Hello from Firebase!");
       });
  </code></pre>