title: How to verify an email before making it the primary (Firebase Authentication)
body: <p>In firebase auth I am able to verify a users email only after I have made it their primary email for logging in.
  I can change the users email this way:</p>
  
  <pre><code>var user = firebase.auth().currentUser;
  
  user.updateEmail("user@example.com").then(function() {
    // Update successful.
  }).catch(function(error) {
    // An error happened.
  });
  </code></pre>
  
  <p>Then I can verify the email after it has been set this way:</p>
  
  <pre><code>var user = firebase.auth().currentUser;
  
  user.sendEmailVerification().then(function() {
    // Email sent.
  }).catch(function(error) {
    // An error happened.
  });
  </code></pre>
  
  <p>What I want to do is verify the email BEFORE it is set to the users primary email.</p>