fix regression in undomanager

node_modules/ace/lib/ace/edit_session.js

@@ -1198,7 +1198,7 @@ EditSession.$uid = 0;
         var range, point;
         var lastDeltaIsInsert;
 
-        for (var i = 1; i < deltas.length; i++) {
+        for (var i = 0; i < deltas.length; i++) {
             var delta = deltas[i];
             if (!delta.start) continue; // skip folds
             if (!range) {