Consistently use setters to set event handlers in native APIs.

tests/standalone/src/SocketManyConnectionsTest.dart

 // Copyright (c) 2011, 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.
 //
 // Test creating a large number of socket connections.
 
 final SERVERINIT = 0;
 final SERVERSHUTDOWN = -1;
 final CONNECTIONS = 200;
 final HOST = "127.0.0.1";
@@ skipping 19 matching lines @@
         for (int i = 0; i < CONNECTIONS; i++) {
           _sockets[i].close();
         }
         shutdown();
       }
     }
 
     for (int i = 0; i < CONNECTIONS; i++) {
       _sockets[i] = new Socket(HOST, _port);
       if (_sockets[i] !== null) {
-        _sockets[i].setConnectHandler(connectHandler);
+        _sockets[i].connectHandler = connectHandler;
       } else {
         Expect.fail("socket creation failed");
       }
     }
   }
 
   void start() {
     _receivePort.receive((var message, SendPort replyTo) {
       _port = message;
       run();
@@ skipping 24 matching lines @@
         _client.close();
       }
 
       void errorHandler() {
         print("Socket error");
         _client.close();
       }
 
       _client = _server.accept();
       _connections++;
-      _client.setCloseHandler(closeHandler);
-      _client.setErrorHandler(errorHandler);
+      _client.closeHandler = closeHandler;
+      _client.errorHandler = errorHandler;
     }
 
     void errorHandlerServer() {
       print("Server socket error");
       _server.close();
     }
 
     this.port.receive((message, SendPort replyTo) {
       if (message == SERVERINIT) {
         _server = new ServerSocket(HOST, 0, 10);
         Expect.equals(true, _server !== null);
-        _server.setConnectionHandler(connectionHandler);
-        _server.setErrorHandler(errorHandlerServer);
+        _server.connectionHandler = connectionHandler;
+        _server.errorHandler = errorHandlerServer;
         replyTo.send(_server.port, null);
       } else if (message == SERVERSHUTDOWN) {
         _server.close();
         this.port.close();
       }
     });
   }
 
   ServerSocket _server;
   int _connections = 0;
 }
 
 main() {
   SocketManyConnectionsTest test = new SocketManyConnectionsTest.start();
 }