Add writeHeaders argument to HttpResponse::detachSocket.

sdk/lib/io/http.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;
 
 /**
  * HTTP status codes.
  */
 abstract class HttpStatus {
@@ skipping 1110 matching lines @@
    */
   Future redirect(Uri location, {int status: HttpStatus.MOVED_TEMPORARILY});
 
   /**
    * Detaches the underlying socket from the HTTP server. When the
    * socket is detached the HTTP server will no longer perform any
    * operations on it.
    *
    * This is normally used when a HTTP upgrade request is received
    * and the communication should continue with a different protocol.
+   *
+   * If [writeHeaders] is `true`, the status line and [headers] will be written
+   * to the socket before it's detached. If `false`, the socket is detached
+   * immediately, without any data written to the socket. Default is `true`.
    */
-  Future<Socket> detachSocket();
+  Future<Socket> detachSocket({bool writeHeaders: true});
 
   /**
    * Gets information about the client connection. Returns [:null:] if the
    * socket is not available.
    */
   HttpConnectionInfo get connectionInfo;
 }
 
 
 /**
@@ skipping 770 matching lines @@
 class RedirectException implements HttpException {
   final String message;
   final List<RedirectInfo> redirects;
 
   const RedirectException(this.message, this.redirects);
 
   String toString() => "RedirectException: $message";
 
   Uri get uri => redirects.last.location;
 }