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

tests/standalone/io/http_proxy_configuration_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 "package:expect/expect.dart";
 import "dart:io";
-import "dart:uri";
 
 expect(expected, String uri, environment) {
   Expect.equals(expected,
                 HttpClient.findProxyFromEnvironment(Uri.parse(uri),
                                                     environment: environment));
 }
 
 expectDirect(String uri, environment) {
   Expect.equals("DIRECT",
                 HttpClient.findProxyFromEnvironment(Uri.parse(uri),
@@ skipping 64 matching lines @@
                 "no_proxy": ".com"});
   expectDirect("http://www.google.com",
                {"http_proxy": "www.proxy.com:8080",
                 "no_proxy": ",,  , www.google.edu,,.com    "});
   expectDirect("http://www.google.edu",
                {"http_proxy": "www.proxy.com:8080",
                 "no_proxy": ",,  , www.google.edu,,.com    "});
   expectDirect("http://www.google.com",
                {"https_proxy": "www.proxy.com:8080"});
 }