Refactor Future constructors.

sdk/lib/io/websocket_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 String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 class _WebSocketMessageType {
   static const int NONE = 0;
@@ skipping 367 matching lines @@
 
   static Future<WebSocket> _upgrade(HttpRequest request) {
     var response = request.response;
     if (!_isUpgradeRequest(request)) {
       // Send error response and drain the request.
       request.listen((_) {}, onDone: () {
         response.statusCode = HttpStatus.BAD_REQUEST;
         response.contentLength = 0;
         response.close();
       });
-      return new Future.immediateError(
+      return new Future.error(
           new WebSocketException("Invalid WebSocket upgrade request"));
     }
 
     // Send the upgrade response.
     response.statusCode = HttpStatus.SWITCHING_PROTOCOLS;
     response.headers.add(HttpHeaders.CONNECTION, "Upgrade");
     response.headers.add(HttpHeaders.UPGRADE, "websocket");
     String key = request.headers.value("Sec-WebSocket-Key");
     SHA1 sha1 = new SHA1();
     sha1.add("$key$_webSocketGUID".codeUnits);
@@ skipping 288 matching lines @@
       if (data != null) {
         _socket.add(data);
       }
     } catch (_) {
       // The socket can be closed before _socket.done have a chance
       // to complete.
       _writeClosed = true;
     }
   }
 }