Need to add a delay between calls to `createDriver` and `driver.get`

[johnpryan]

In DartPad, webdriver tests are failing unless an artificial delay is added:

  setUp(() async {
    // Connect to it with the webdriver package
    driver = await createDriver(
        uri: Uri.parse('http://localhost:4444/wd/hub/'),
        desired: Capabilities.chrome);

    await Future.delayed(Duration(milliseconds: 2000));

    // Go to your page
    await driver.get('http://localhost:8000/');
    await waitForPageToStabilize();
  });

dart-lang/dart-pad#2360
dart-lang/dart-pad#2361