Add isolate tag-profile and better handling of errors

runtime/bin/vmservice/client/lib/service_html.dart

 // Copyright (c) 2014, 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 service_html;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:html';
 
@@ skipping 18 matching lines @@
       // want to connect on the default port.
       host = 'http://127.0.0.1:8181/';
     }
   }
 
   Future<String> getString(String id) {
     Logger.root.info('Fetching $id from $host');
     return HttpRequest.getString(host + id).catchError((error) {
       // If we get an error here, the network request has failed.
       Logger.root.severe('HttpRequest.getString failed.');
+      var request = error.target;
       return JSON.encode({
-          'type': 'Error',
+          'type': 'ServiceException',
           'id': '',
-          'kind': 'NetworkError',
+          'response': error.target.responseText,
+          'kind': 'NetworkException',
           'message': 'Could not connect to service. Check that you started the'
                      ' VM with the following flags:\n --enable-vm-service'
-                    ' --pin-isolates'
+                    ' --pause-isolates-on-exit'
         });
     });
   }
 }
 
 class DartiumVM extends VM {
   final Map _outstandingRequests = new Map();
   int _requestSerial = 0;
 
   DartiumVM() : super() {
@@ skipping 20 matching lines @@
     message['id'] = idString;
     message['method'] = 'observatoryQuery';
     message['query'] = '/$path';
     _requestSerial++;
     var completer = new Completer();
     _outstandingRequests[idString] = completer;
     window.parent.postMessage(JSON.encode(message), '*');
     return completer.future;
   }
 }