fix: #2370 IE10 drag-and-drop support (#2426)

* Fix redraw order
* Fix IE10 support for dnd

Author: yotamberk

lib/timeline/component/ItemSet.js

@@ -1850,7 +1850,7 @@ ItemSet.prototype._onAddItem = function (event) {
     };
 
     if (event.type == 'drop') {
-      var itemData = JSON.parse(event.dataTransfer.getData("text/plain"))
+      var itemData = JSON.parse(event.dataTransfer.getData("text"))
       newItemData.content = itemData.content; // content is required 
       newItemData.type = itemData.type || 'box';
       newItemData[this.itemsData._fieldId] = itemData.id || util.randomUUID();