Fixed invalid variable

Author: Giegling

intro.js

@@ -762,7 +762,6 @@
    * @param {Object} targetElement
    */
   function _showElement(targetElement) {
-
     if (typeof (this._introChangeCallback) !== 'undefined') {
       this._introChangeCallback.call(this, targetElement.element);
     }
@@ -839,7 +838,7 @@
         _placeTooltip.call(self, targetElement.element, oldtooltipContainer, oldArrowLayer, oldHelperNumberLayer);
 
         //change active bullet
-        if (this._options.showBullets === false) {
+        if (self._options.showBullets) {
             oldReferenceLayer.querySelector('.introjs-bullets li > a.active').className = '';
             oldReferenceLayer.querySelector('.introjs-bullets li > a[data-stepnumber="' + targetElement.step + '"]').className = 'active';
         }