Update for api changes

src/notebook/notebook/model.ts

@@ -321,8 +321,11 @@ class NotebookModel extends DocumentModel implements INotebookModel {
         continue;
       }
     }
+    this.cells.beginCompoundOperation();
     this.cells.clear();
     this.cells.pushAll(cells);
+    this.cells.endCompoundOperation();
+
     let oldValue = 0;
     let newValue = 0;
     if (value.nbformat !== this._nbformat) {

src/notebook/notebook/widget.ts

@@ -6,7 +6,7 @@ import {
 } from '@jupyterlab/services';
 
 import {
-  IIterable, each
+  each
 } from 'phosphor/lib/algorithm/iteration';
 
 import {

src/notebook/output-area/model.ts

@@ -5,10 +5,6 @@ import {
   IKernel, KernelMessage
 } from '@jupyterlab/services';
 
-import {
-  EmptyIterator, IIterator
-} from 'phosphor/lib/algorithm/iteration';
-
 import {
   JSONObject
 } from 'phosphor/lib/algorithm/json';