build(examples): upgrade to protractor 4.0.9 (#12803)

closes #12798

modules/@angular/benchpress/test/firefox_extension/sample_benchmark.ts

@@ -6,6 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {$, browser} from 'protractor';
+
 var benchpress = require('../../index.js');
 var runner = new benchpress.Runner([
   // use protractor as Webdriver client