code: function makeApplicationVerifier(submitButtonId) {
    var container = recaptchaSize === 'invisible' ?
        submitButtonId :
        'recaptcha-container';
    applicationVerifier = new firebase.auth.RecaptchaVerifier(container,
        {'size': recaptchaSize});
  }
docs: Initializes the ApplicationVerifier.
  @param {string} submitButtonId The ID of the DOM element of the button to
  which we attach the invisible reCAPTCHA. This is required even in visible
  mode.