Address additional comments from http://codereview.chromium.org/9956062/

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 463 matching lines @@
 
   void _connectionEstablished(Socket socket) {
     _socket = socket;
     // Register handler for socket events.
     _socket.onData = _onData;
     _socket.onClosed = _onClosed;
     _socket.onError = _onError;
   }
 
   bool _write(List<int> data, [bool copyBuffer = false]) {
-    if (!_error) {
+    if (!_error && !_closing) {
       return _socket.outputStream.write(data, copyBuffer);
     }
   }
 
   bool _writeFrom(List<int> buffer, [int offset, int len]) {
-    if (!_error) {
+    if (!_error && !_closing) {
       return _socket.outputStream.writeFrom(buffer, offset, len);
     }
   }
 
   bool _close() {
     _socket.close();
   }
 
   void _onData() {
     int available = _socket.available();
     if (available == 0) {
       return;
     }
 
     ByteArray buffer = new ByteArray(available);
     int bytesRead = _socket.readList(buffer, 0, available);
     if (bytesRead > 0) {
       int parsed = _httpParser.writeList(buffer, 0, bytesRead);
       if (parsed != bytesRead) {
         // TODO(sgjesse): Error handling.
         _socket.close();
       }
     }
   }
 
   void _onClosed() {
+    _closing = true;
     _onConnectionClosed(null);
   }
 
   void _onError(Exception e) {
     // If an error occurs, make sure to close the socket if one is associated.
     _error = true;
     if (_socket != null) {
       _socket.close();
     }
     _onConnectionClosed(e);
@@ skipping 55 matching lines @@
         // Don't call onClosed if onError has been called.
         onClosed();
       }
       return;
     }
 
     // Processing a request.
     if (e == null) {
       // Indicate connection close to the HTTP parser.
       _httpParser.connectionClosed();
-      _closing = true;
     }
   }
 
   void _onRequestStart(String method, String uri) {
     // Create new request and response objects for this request.
     _request = new _HttpRequest(this);
     _response = new _HttpResponse(this);
     _request._onRequestStart(method, uri);
   }
 
@@ skipping 642 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?
 }