code: function onUpdateConfirmPhoneVerification() {
    if (!activeUser()) {
      alertError('You need to sign in before linking an account.');
      return;
    }
    var verificationId = $('#link-reauth-phone-verification-id').val();
    var verificationCode = $('#link-reauth-phone-verification-code').val();
    var credential = firebase.auth.PhoneAuthProvider.credential(
        verificationId, verificationCode);
    activeUser().updatePhoneNumber(credential).then(function() {
      refreshUserData();
      alertSuccess('Phone number updated!');
    }, onAuthError);
  }
docs: Updates the user's phone number.