Consistently use setters to set event handlers in native APIs.

tests/standalone/src/EchoServerStreamTest.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.
 //
 // Echo server test program to test socket streams.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
@@ skipping 72 matching lines @@
             } else {
               shutdown();
             }
           }
         }
 
         if (_messages % 2 == 0) data = new List<int>(MSGSIZE);
         inputStream.dataHandler = dataReceived;
       }
 
-      _socket.setCloseHandler(closeHandler);
-      _socket.setErrorHandler(errorHandler);
+      _socket.closeHandler = closeHandler;
+      _socket.errorHandler = errorHandler;
       stream.write(_buffer);
       dataSent();
     }
 
     _socket = new Socket(EchoServer.HOST, _port);
     if (_socket !== null) {
-      _socket.setConnectHandler(connectHandler);
+      _socket.connectHandler = connectHandler;
     } else {
       Expect.fail("socket creation failed");
     }
   }
 
   void start() {
     _receivePort.receive((var message, SendPort replyTo) {
       _port = message;
       sendData();
     });
@@ skipping 45 matching lines @@
       }
 
       void errorHandler() {
         print("Socket error");
         _client.close();
       }
 
       _client = _server.accept();
       inputStream = _client.inputStream;
       inputStream.dataHandler = dataReceived;
-      _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 == EchoServerGame.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 == EchoServerGame.SERVERSHUTDOWN) {
         _server.close();
         this.port.close();
       }
     });
   }
 
   ServerSocket _server;
 }
 
 main() {
   EchoServerStreamTest.testMain();
 }