Avoid double reporting of errors to HTTPServer onError callback

runtime/bin/http_impl.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.
 
 class _HttpRequestResponseBase {
   _HttpRequestResponseBase(_HttpConnectionBase this._httpConnection)
       : _contentLength = -1,
         _keepAlive = false,
         _headers = new Map();
 
@@ skipping 591 matching lines @@
   void _onDataEnd() {
     // Phase might already have gone to PHASE_IDLE if the response is
     // sent without waiting for request body.
     if (_phase == PHASE_REQUEST) {
       _phase = PHASE_RESPONSE;
     }
     _request._onDataEnd();
   }
 
   void _propagateError(Exception e) {
-    if (_server._onError != null) {
-      _server._onError(e);
-    }
     if (_request != null && _request._streamErrorHandler != null) {
       _request._streamErrorHandler(e);
     }
     if (_response != null && _response._streamErrorHandler != null) {
       _response._streamErrorHandler(e);
     }
   }
 
   HttpServer _server;
   HttpRequest _request;
@@ skipping 572 matching lines @@
     sockets.addFirst(socketConn);
     socketConn._markReturned();
   }
 
   Function _onOpen;
   Map<String, Queue<_SocketConnection>> _openSockets;
   Set<_SocketConnection> _activeSockets;
   Timer _evictionTimer;
   bool _shutdown;  // Has this HTTP client been shutdown?
 }