Don't add ':443' to host header, when the connection is secure.

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;
 
 const int _OUTGOING_BUFFER_SIZE = 8 * 1024;
 
 class _HttpIncoming extends Stream<List<int>> {
   final int _transferLength;
@@ skipping 398 matching lines @@
 abstract class _HttpOutboundMessage<T> extends _IOSinkImpl {
   // Used to mark when the body should be written. This is used for HEAD
   // requests and in error handling.
   bool _encodingSet = false;
 
   final Uri _uri;
   final _HttpOutgoing _outgoing;
 
   final _HttpHeaders headers;
 
-  _HttpOutboundMessage(this._uri,
+  _HttpOutboundMessage(Uri uri,
                        String protocolVersion,
                        _HttpOutgoing outgoing)
       : super(outgoing, null),
-        headers = new _HttpHeaders(protocolVersion),
+        _uri = uri,
+        headers = new _HttpHeaders(
+            protocolVersion,
+            defaultPortForScheme: uri.scheme == 'https' ?
+                HttpClient.DEFAULT_HTTPS_PORT :
+                HttpClient.DEFAULT_HTTP_PORT),
         _outgoing = outgoing {
     _outgoing.outbound = this;
     _encodingMutable = false;
   }
 
   int get contentLength => headers.contentLength;
   void set contentLength(int contentLength) {
     headers.contentLength = contentLength;
   }
 
@@ skipping 2138 matching lines @@
   const _RedirectInfo(this.statusCode, this.method, this.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)';
 }