code: function( cls ) {
  				var classes = this.getCustomData( 'classes' );
  				if ( !this.hasClass( cls ) ) {
  					!classes && ( classes = [] ), classes.push( cls );
  					this.setCustomData( 'classes', classes );
  					this.addClass( cls );
  				}
  			}
docs: Adds a CSS class name to this editable that needs to be removed on detaching.
  
  @param {String} className The class name to be added.
  @see CKEDITOR.dom.element#addClass