Remove navigation mode/more rows element

src/utils/TestUtils.test.ts

@@ -10,9 +10,6 @@ import * as Browser from '../shared/utils/Browser';
 import { ITheme, IDisposable } from 'xterm';
 
 export class MockTerminal implements ITerminal {
-  enterNavigationMode(): void {
-    throw new Error('Method not implemented.');
-  }
   getOption(key: any): any {
     throw new Error('Method not implemented.');
   }