Make #maxRedirects and #followRedirects work for the dart:io HTTP client.

pkg/http/test/utils.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 utils;
 
 import 'dart:io';
 import 'dart:json';
 import 'dart:uri';
 
@@ skipping 18 matching lines @@
       (request, response) {
     response.statusCode = 400;
     response.contentLength = 0;
     response.outputStream.close();
   });
 
   _server.addRequestHandler((request) => request.path == '/loop',
       (request, response) {
     var n = int.parse(new Uri.fromString(request.uri).query);
     response.statusCode = 302;
-    response.headers.set('location', '/loop?${n + 1}');
+    response.headers.set('location',
+        serverUrl.resolve('/loop?${n + 1}').toString());
     response.contentLength = 0;
     response.outputStream.close();
   });
 
   _server.addRequestHandler((request) => request.path == '/redirect',
       (request, response) {
     response.statusCode = 302;
-    response.headers.set('location', '/');
+    response.headers.set('location', serverUrl.resolve('/').toString());
     response.contentLength = 0;
     response.outputStream.close();
   });
 
   _server.defaultRequestHandler = (request, response) {
     consumeInputStream(request.inputStream).then((requestBodyBytes) {
       response.statusCode = 200;
       response.headers.contentType = new ContentType("application", "json");
 
       var requestBody;
@@ skipping 106 matching lines @@
 const Matcher throwsRedirectLimitExceededException =
     const Throws(isRedirectLimitExceededException);
 
 class _RedirectLimitExceededException extends TypeMatcher {
   const _RedirectLimitExceededException() :
       super("RedirectLimitExceededException");
 
   bool matches(item, MatchState matchState) =>
     item is RedirectLimitExceededException;
 }