code: function loadRecaptcha(container) {
    var root = goog.dom.getElement(container);
    var recaptchaContainer =
        goog.dom.getElementByClass('firebaseui-recaptcha-container', root);
    recaptchaContainer.style.display = 'block';
    var img = goog.dom.createElement('img');
    img.src = '../image/test/recaptcha-widget.png';
    recaptchaContainer.appendChild(img);
  }
docs: Simulates a reCAPTCHA being rendered for UI testing. This will just load a
  mock visible reCAPTCHA in the reCAPTCHA element.
  @param {Element} container The root container that holds the reCAPTCHA.