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

tests/standalone/io/http_stream_close_test.dart

 // Copyright (c) 2013, 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:uri";
 
 main() {
   bool serverOnClosed = false;
   bool clientOnClosed = false;
   bool requestOnClosed = false;
 
   HttpServer.bind("127.0.0.1", 0).then((server) {
     var client = new HttpClient();
 
     checkDone() {
@@ skipping 29 matching lines @@
         .then((response) {
           response.listen(
               (_) {},
               onDone: () {
                 requestOnClosed = true;
                 checkDone();
               });
         });
   });
 }