Merge the dart:uri library into dart:core and update the Uri class

pkg/oauth2/test/client_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.
 
 library client_test;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:json' as JSON;
-import 'dart:uri';
 
 import 'package:http/http.dart' as http;
 import 'package:oauth2/oauth2.dart' as oauth2;
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
 
 final Uri requestUri = Uri.parse("http://example.com/resource");
 
 final Uri tokenEndpoint = Uri.parse('http://example.com/token');
@@ skipping 199 matching lines @@
         return new Future.value(new http.Response('bad job', 401,
                 headers: {'www-authenticate': 'Bearer'}));
       });
 
       expect(
           client.get(requestUri).then((response) => response.statusCode),
           completion(equals(401)));
     });
   });
 }