Refactor VM service IDs

tests/standalone/vmservice/isolate_echo_test.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 isolate_echo_test;
 
 import 'test_helper.dart';
 import 'package:expect/expect.dart';
 
 class EchoRequestTest extends VmServiceRequestHelper {
   EchoRequestTest(port, id) :
-      super('http://127.0.0.1:$port/isolates/$id/_echo/foo/bar?a=b&k=&d=e&z=w');
+      super('http://127.0.0.1:$port/$id/_echo/foo/bar?a=b&k=&d=e&z=w');
 
   onRequestCompleted(Map reply) {
     Expect.equals('message', reply['type']);
 
     Expect.equals(3, reply['message']['arguments'].length);
     Expect.equals('_echo', reply['message']['arguments'][0]);
     Expect.equals('foo', reply['message']['arguments'][1]);
     Expect.equals('bar', reply['message']['arguments'][2]);
 
     Expect.equals(4, reply['message']['option_keys'].length);
@@ skipping 28 matching lines @@
   process.launch().then((port) {
     var test = new IsolateListTest(port);
     test.makeRequest().then((_) {
       var echoRequestTest = new EchoRequestTest(port, test._isolateId);
       echoRequestTest.makeRequest().then((_) {
         process.requestExit();
       });
     });
   });
 }