Move pub into sdk/lib/_internal.

sdk/lib/_internal/pub/test/oauth2/with_a_pre_existing_credentials_does_not_authenticate_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 a pre-existing credentials.json does not authenticate', () {
     d.validPackage.create();
 
     var server = new ScheduledServer();
     d.credentialsFile(server, 'access token').create();
     var pub = startPublish(server);
     confirmPublish(pub);
 
     server.handle('GET', '/packages/versions/new.json', (request) {
       expect(request.headers.value('authorization'),
           equals('Bearer access token'));
 
       request.response.close();
     });
 
     pub.kill();
   });
 }