anchor.diff:      }
       // TODO(ajohnsen): Listen for socket close events.
       if (!_idleConnections.containsKey(connection.key)) {
  -      _idleConnections[connection.key] = new Queue();
  -    }
  -    _idleConnections[connection.key].addLast(connection);
  +      _idleConnections[connection.key] = new Set();
  +    }
  +    _idleConnections[connection.key].add(connection);
     }
   
     // Remove a closed connnection from the active set.
  
positive.code:   static const int DEFAULT_EVICTION_TIMEOUT = 60000;
    bool _closing = false;
  
    final Map<String, Queue<_HttpClientConnection>> _idleConnections
        = new Map<String, Queue<_HttpClientConnection>>();
    final Set<_HttpClientConnection> _activeConnections
        = new Set<_HttpClientConnection>();
    final List<_Credentials> _credentials = [];
  
negative.code:       int port = proxy.isDirect ? uriPort: proxy.port;
        String key = isSecure ? "ssh:$host:$port" : "$host:$port";
        if (_idleConnections.containsKey(key)) {
          var connection = _idleConnections[key].first;
          _idleConnections[key].remove(connection);
          if (_idleConnections[key].isEmpty) {
            _idleConnections.remove(key);
          }
  