Refactor Isolate name format, storage and log

runtime/observatory/tests/service/set_name_rpc_test.dart

 // Copyright (c) 2015, 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.
 // VMOptions=--error_on_bad_type --error_on_bad_override --vm-name=Walter
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'dart:async';
 
 var tests = [
   (Isolate isolate) async {
-    expect(isolate.name, equals('set_name_rpc_test.dart\$main'));
+    expect(isolate.name, equals('set_name_rpc_test.dart\:main()'));

[rmacnak, 2017/08/24 19:00:19]

The colon doesn't need to be escaped.

[cbernaschina, 2017/08/24 20:19:33]

Done.

 
     Completer completer = new Completer();
     var stream = await isolate.vm.getEventStream(VM.kIsolateStream);
     var subscription;
     subscription = stream.listen((ServiceEvent event) {
       if (event.kind == ServiceEvent.kIsolateUpdate) {
         expect(event.owner.type, equals('Isolate'));
         expect(event.owner.name, equals('Barbara'));
         subscription.cancel();
         completer.complete();
       }
     });
 
     var result = await isolate.setName('Barbara');
     expect(result.type, equals('Success'));
 
     await completer.future;
     expect(isolate.name, equals('Barbara'));
   }
 ];
 
 main(args) async => runIsolateTests(args, tests);