Reduce copying in sending service responses.

runtime/bin/vmservice/vmservice_io.dart

 // Copyright (c) 2013, 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.
 
 library vmservice_io;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:isolate';
+import 'dart:typed_data';
 import 'dart:_vmservice';
 
 part 'loader.dart';
 part 'server.dart';
 
 // The TCP ip/port that the HTTP server listens on.
 int _port;
 String _ip;
 // Should the HTTP server auto start?
 bool _autoStart;
@@ skipping 192 matching lines @@
     Timer.run(() {});
   }
   scriptLoadPort.handler = _processLoadRequest;
   // Register signal handler after a small delay to avoid stalling main
   // isolate startup.
   _registerSignalHandlerTimer = new Timer(shortDelay, _registerSignalHandler);
   return scriptLoadPort;
 }
 
 _shutdown() native "VMServiceIO_Shutdown";