Add the decorator parameter to the handlers for the attach and detach the dropdown (otherwise the container is undefined)

src/js/select2/dropdown/attachBody.js

@@ -80,7 +80,7 @@ define([
     this.$dropdownContainer.detach();
   };
 
-  AttachBody.prototype._attachPositioningHandler = function (container) {
+  AttachBody.prototype._attachPositioningHandler = function (decorated, container) {
     var self = this;
 
     var scrollEvent = 'scroll.select2.' + container.id;
@@ -107,7 +107,7 @@ define([
     });
   };
 
-  AttachBody.prototype._detachPositioningHandler = function (container) {
+  AttachBody.prototype._detachPositioningHandler = function (decorated, container) {
     var scrollEvent = 'scroll.select2.' + container.id;
     var resizeEvent = 'resize.select2.' + container.id;
     var orientationEvent = 'orientationchange.select2.' + container.id;