Move pub into sdk/lib/_internal.

sdk/lib/_internal/pub/test/oauth2/with_an_expired_credentials_without_a_refresh_token_authenticates_again_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:io';
 import 'dart:json' as json;
 
 import 'package:scheduled_test/scheduled_test.dart';
 import 'package:scheduled_test/scheduled_server.dart';
 
-import '../../../pub/io.dart';
-import '../../../pub/utils.dart';
+import '../../lib/src/io.dart';
+import '../../lib/src/utils.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 main() {
   initConfig();
   integration('with an expired credentials.json without a refresh token, '
        'authenticates again and saves credentials.json', () {
     d.validPackage.create();
 
@@ skipping 16 matching lines @@
       request.response.close();
     });
 
     // After we give pub an invalid response, it should crash. We wait for it to
     // do so rather than killing it so it'll write out the credentials file.
     pub.shouldExit(1);
 
     d.credentialsFile(server, 'new access token').validate();
   });
 }