Returns the HTML containing the ReCaptcha element.
Used in __toString() and to be used when $data['captchaRender'] is set to false. It is not called when the element is frozen, see getFrozenHtml() for that case. This method is also not called when the captcha has been solved, since $data['captchaSolved'] is shown then.
Overrides
HTML_QuickForm2_Element_Captcha::getCaptchaHtml() (Returns the HTML for the captcha (question + input element if applicable))