title: Google Recaptcha enables disabled submit button
body: <p>I'm using <code>reCaptcha v2 invisible</code>.  I have a simple form with a <code>disabled</code> submit button.  Google reCAPTCHA is enabling my disabled button.  </p>
  
  <pre><code>&lt;script src="https://www.google.com/recaptcha/api.js"&gt;&lt;/script&gt;
  
  &lt;form action="/action_page.php" id="referral-form"&gt;
      First name:
      &lt;br&gt;
      &lt;input type="text" name="firstname"&gt;
      &lt;br&gt;
      Last name:
      &lt;br&gt;
      &lt;input type="text" name="lastname"&gt;
      &lt;br&gt;
      &lt;input type="submit" id="form-submit-btn" disabled="disabled" class="g-recaptcha" data-callback='onSubmit' data-sitekey="***************" value="Submit"&gt;
  &lt;/form&gt;
  
  function onSubmit() {
      if (grecaptcha.getResponse() !== "") {
          $('#referral-form').submit();
      }
          grecaptcha.reset();
  }
  </code></pre>
  
  <p>When I remove <code>class="g-recaptcha"</code> the button is properly disabled.</p>