Fix type error in http_impl.dart.

sdk/lib/io/http_impl.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.
 
 part of dart.io;
 
 class _HttpIncoming extends Stream<List<int>> {
   final int _transferLength;
   final Completer _dataCompleter = new Completer();
   Stream<List<int>> _stream;
@@ skipping 1552 matching lines @@
           }
           return send(info);
         });
   }
 
   Future<HttpClientRequest> _openUrlFromRequest(String method,
                                                 Uri uri,
                                                 _HttpClientRequest previous) {
     // If the new URI is relative (to either '/' or some sub-path),
     // construct a full URI from the previous one.
-    URI resolved = previous.uri.resolveUri(uri);
+    Uri resolved = previous.uri.resolveUri(uri);
     return openUrl(method, resolved).then((_HttpClientRequest request) {
           // Only follow redirects if initial request did.
           request.followRedirects = previous.followRedirects;
           // Allow same number of redirects.
           request.maxRedirects = previous.maxRedirects;
           // Copy headers.
           for (var header in previous.headers._headers.keys) {
             if (request.headers[header] == null) {
               request.headers.set(header, previous.headers[header]);
             }
@@ skipping 863 matching lines @@
   final Uri location;
 }
 
 String _getHttpVersion() {
   var version = Platform.version;
   // Only include major and minor version numbers.
   int index = version.indexOf('.', version.indexOf('.') + 1);
   version = version.substring(0, index);
   return 'Dart/$version (dart:io)';
 }