Cleanup vm_service library loading.

runtime/bin/vmservice/vmservice.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;
 
 import 'dart:async';
 import 'dart:json' as JSON;
-// TODO(11927): Factor 'dart:io' dependency into separate library.
-import 'dart:io';
 import 'dart:isolate';
 import 'dart:typed_data';
 import 'dart:utf' as UTF;
 
+part 'constants.dart';
+part 'resources.dart';
+part 'running_isolate.dart';
+part 'running_isolates.dart';
+part 'service_request.dart';
+part 'service_request_router.dart';
 
-class VmService {
-  static VmService _instance;
+class VMService {
+  static VMService _instance;
   RunningIsolates runningIsolates = new RunningIsolates();
 
   void controlMessageHandler(int code, SendPort sp) {
     switch (code) {
       case Constants.ISOLATE_STARTUP_MESSAGE_ID:
         runningIsolates.isolateStartup(sp);
       break;
       case Constants.ISOLATE_SHUTDOWN_MESSAGE_ID:
         runningIsolates.isolateShutdown(sp);
       break;
     }
   }
 
   void messageHandler(message, SendPort replyTo) {
     if (message is List && message.length == 2) {
       controlMessageHandler(message[0], message[1]);
     }
   }
 
-  VmService._internal() {
+  VMService._internal() {
     port.receive(messageHandler);
   }
 
-  factory VmService() {
-    if (VmService._instance == null) {
-      VmService._instance = new VmService._internal();
+  factory VMService() {
+    if (VMService._instance == null) {
+      VMService._instance = new VMService._internal();
     }
     return _instance;
   }
 }
 
 void sendServiceMessage(SendPort sp, ReceivePort rp, Object m)
     native "SendServiceMessage";