Convert pkg/http to use "package:" imports.

pkg/http/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:io';
 
-import '../../unittest/lib/unittest.dart';
-import '../lib/http.dart' as http;
-import '../lib/src/utils.dart';
+import 'package:unittest/unittest.dart';
+import 'package:http/http.dart' as http;
+import 'package:http/src/utils.dart';
 import 'utils.dart';
 
 void main() {
   setUp(startServer);
   tearDown(stopServer);
 
   test('#send a StreamedRequest', () {
     var client = new http.Client();
     var request = new http.StreamedRequest("POST", serverUrl);
     request.headers[HttpHeaders.CONTENT_TYPE] =
@@ skipping 13 matching lines @@
         'content-type': ['application/json; charset=utf-8'],
         'transfer-encoding': ['chunked']
       },
       'body': '{"hello": "world"}'
     }))));
 
     request.stream.writeString('{"hello": "world"}');
     request.stream.close();
   });
 }