dispose view model properly

src/vs/workbench/contrib/notebook/browser/notebookEditor.ts

@@ -273,6 +273,7 @@ export class NotebookEditor extends BaseEditor implements INotebookEditor, Noteb
 
 		if (this.notebookViewModel && !this.notebookViewModel.isDirty()) {
 			this.notebookService.destoryNotebookDocument(this.viewType!, this.notebookViewModel!.notebookDocument);
+			this.notebookViewModel.dispose();
 			this.notebookViewModel = undefined;
 		}
 

src/vs/workbench/contrib/notebook/browser/viewModel/notebookViewModel.ts

@@ -225,6 +225,7 @@ export class NotebookViewModel extends Disposable {
 		this._localStore.clear();
 		this._viewCells.forEach(cell => {
 			cell.save();
+			cell.dispose();
 		});
 
 		super.dispose();