Fix a number of HTTP issues

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();
   var conn = client.get('www.google.com', 80, '/');
 
   conn.onRequest = (HttpClientRequest request) {
     request.outputStream.close();
   };
   conn.onResponse = (HttpClientResponse response) {
     Expect.isTrue(response.statusCode < 500);
     response.inputStream.onData = () {
       response.inputStream.read();
     };
     response.inputStream.onClosed = () {
       client.shutdown();
     };
   };
-  conn.onError = (error) => Expect.fail("Unexpected IO error");
+  conn.onError = (error) => Expect.fail("Unexpected IO error $error");
 }
 
 int testGoogleUrlCount = 0;
 void testGoogleUrl() {
   HttpClient client = new HttpClient();
 
   void testUrl(String url) {
     var requestUri = new Uri.fromString(url);
     var conn = client.getUrl(requestUri);
 
@@ skipping 41 matching lines @@
     port.close();  // We expect onError to be called, due to bad host name.
   };
 }
 
 void main() {
   testGoogle();
   testGoogleUrl();
   testInvalidUrl();
   testBadHostName();
 }