code: function onReauthenticateWithEmailLink() {
    var email = $('#link-with-email-link-email').val();
    var link = $('#link-with-email-link-link').val() || undefined;
    var credential = firebase.auth.EmailAuthProvider
        .credentialWithLink(email, link);
    activeUser().reauthenticateWithCredential(credential)
        .then(function(result) {
          logAdditionalUserInfo(result);
          refreshUserData();
          alertSuccess('User reauthenticated!');
        }, onAuthError);
  }
docs: Re-authenticate a user with email link credential.