Fixed bug #33962. Fixed issue with undo in fast collaborative.

word/Editor/CollaborativeEditing.js

@@ -762,19 +762,23 @@ CWordCollaborativeEditing.prototype.Undo = function()
 	var oHistory = AscCommon.History;
 	oHistory.CreateNewPointForCollectChanges();
 	var oDrawing;
-	for(var sId in mapDrawings){
-	    if(mapDrawings.hasOwnProperty(sId)){
+	for (var sId in mapDrawings)
+	{
+		if (mapDrawings.hasOwnProperty(sId))
+		{
 			oDrawing = mapDrawings[sId];
-            if(!oDrawing.CheckCorrect()){
+			if (!oDrawing.CheckCorrect())
+			{
 				var oParentParagraph = oDrawing.Get_ParentParagraph();
 				oDrawing.Remove_FromDocument(false);
-                if(oParentParagraph){
+				if (oParentParagraph)
+				{
 					mapParagraphs[oParentParagraph.Get_Id()] = oParentParagraph;
 				}
 			}
 		}
-
 	}
+
 	for (var sId in mapDocumentContents)
 	{
 		var oDocumentContent = mapDocumentContents[sId];
@@ -798,6 +802,7 @@ CWordCollaborativeEditing.prototype.Undo = function()
 		arrReverseChanges.push(oHistoryPoint.Items[nIndex].Data);
 	}
 	oHistory.Remove_LastPoint();
+	this.Clear_DCChanges();
 
 	var oBinaryWriter = AscCommon.History.BinaryWriter;
 	var aSendingChanges = [];

word/Editor/Paragraph.js

@@ -5334,7 +5334,6 @@ Paragraph.prototype =
             if ((para_Hyperlink === CurElement.Type || para_Math === CurElement.Type || para_Field === CurElement.Type) && true === CurElement.Is_Empty() && true !== CurElement.Is_CheckingNearestPos())
             {
                 this.Internal_Content_Remove(CurPos);
-                CurPos++;
             }
             else if (para_Comment === CurElement.Type && false === CurElement.Start)
             {