static comment(text) {
    return SafeHtml.createSafeHtmlSecurityPrivateDoNotAccessOrElse(
        '<!--' + internal.htmlEscape(text) + '-->');
  }
Converts an arbitrary string into an HTML comment by HTML-escaping the
contents and embedding the result between HTML comment markers.

Escaping is needed because Internet Explorer supports conditional comments
and so may render HTML markup within comments.

@param {string} text
@return {!SafeHtml}