function HTML(html, option) {
  this.html = html;
  this.get = lowercase(option) == 'unsafe'
    ? valueFn(html)
    : function htmlSanitize() {
        var buf = [];
        htmlParser(html, htmlSanitizeWriter(buf));
        return buf.join('');
      };
}
HTML class which is the only class which can be used in ng-bind to inline HTML for security
reasons.

@constructor
@param html raw (unsafe) html
@param {string=} option If set to 'usafe', get method will return raw (unsafe/unsanitized) html