Add support for authorization of HTTP client requests

tests/standalone/io/http_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.
 
 #import("dart:io");
 #import("dart:uri");
 #import("dart:isolate");
 
 void testGoogle() {
   HttpClient client = new HttpClient();
@@ skipping 45 matching lines @@
   testUrl('http://www.google.com/abc');
   testUrl('http://www.google.com/?abc');
   testUrl('http://www.google.com/abc?abc');
   testUrl('http://www.google.com/abc?abc#abc');
 }
 
 void testInvalidUrl() {
   HttpClient client = new HttpClient();
   Expect.throws(
       () => client.getUrl(new Uri.fromString('ftp://www.google.com')));
-  Expect.throws(
-      () => client.getUrl(new Uri.fromString('http://usr:pwd@www.google.com')));
 }
 
 void testBadHostName() {
   HttpClient client = new HttpClient();
   HttpClientConnection connection =
       client.get("some.bad.host.name.7654321", 0, "/");
   connection.onRequest = (HttpClientRequest request) {
     Expect.fail("Should not open a request on bad hostname");
   };
   ReceivePort port = new ReceivePort();
   connection.onError = (Exception error) {
     port.close();  // We expect onError to be called, due to bad host name.
   };
 }
 
 void main() {
   testGoogle();
   testGoogleUrl();
   testInvalidUrl();
   testBadHostName();
 }