Preserve the contents of Dart strings with unmatched surrogate halfs by avoiding a UTF16 -> UTF8

runtime/bin/vmservice/observatory/lib/src/service/object.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.
 
 part of service;
 
 /// A [ServiceObject] is an object known to the VM service and is tied
 /// to an owning [Isolate].
 abstract class ServiceObject extends Observable {
   static int LexicalSortName(ServiceObject o1, ServiceObject o2) {
@@ skipping 1260 matching lines @@
   @observable String message;
   @observable dynamic response;
 
   void _update(ObservableMap map, bool mapIsRef) {
     kind = map['kind'];
     message = map['message'];
     response = map['response'];
     name = 'ServiceException $kind';
     vmName = name;
   }
+
+  String toString() => 'ServiceException($message)';
 }
 
 /// A [ServiceEvent] is an asynchronous event notification from the vm.
 class ServiceEvent extends ServiceObject {
   ServiceEvent._empty(ServiceObjectOwner owner) : super._empty(owner);
 
   @observable String eventType;
   @observable ServiceMap breakpoint;
   @observable ServiceMap exception;
   @observable ByteData data;
@@ skipping 1270 matching lines @@
     var v = list[i];
     if ((v is ObservableMap) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is ObservableList) {
       _upgradeObservableList(v, owner);
     } else if (v is ObservableMap) {
       _upgradeObservableMap(v, owner);
     }
   }
 }