Actually close socket, on eviction timeout.

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 1195 matching lines @@
         Date now = new Date.now();
         _openSockets.forEach(
             void _(String key, Queue<_SocketConnection> connections) {
               // As returned connections are added at the head of the
               // list remove from the tail.
               while (!connections.isEmpty()) {
                 _SocketConnection socketConn = connections.last();
                 if (socketConn._idleTime(now).inMilliseconds >
                     DEFAULT_EVICTION_TIMEOUT) {
                   connections.removeLast();
+                  socketConn._socket.close();
                 } else {
                   break;
                 }
               }
             });
       }
       _evictionTimer = new Timer.repeating(10000, _handleEviction);
     }
 
     // Return connection.
     _activeSockets.remove(socketConn);
     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?
 }