mobile dnd polyfill support

angular-drag-and-drop-lists.js

@@ -220,6 +220,18 @@ angular.module('dndLists', [])
       var horizontal = attr.dndHorizontalList && scope.$eval(attr.dndHorizontalList);
       var externalSources = attr.dndExternalSources && scope.$eval(attr.dndExternalSources);
 
+      /**
+       * The dragenter is triggered prior to the dragover and to allow
+       * a drop the event handler must preventDefault().
+       */
+      element.on('dragenter', function (event) {
+        event = event.originalEvent || event;
+
+        if (!isDropAllowed(event)) return true;
+
+        event.preventDefault();
+      });
+
       /**
        * The dragover event is triggered "every few hundred milliseconds" while an element
        * is being dragged over our list, or over an child element.