Don't double-escape in strings in the VM Service, and don't use \u0000 to determine the string lengt

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 1463 matching lines @@
     return isolate.get(id + "/$command");
   }
 
   String toString() => 'Class($vmName)';
 }
 
 class Instance extends ServiceObject {
   @observable Class clazz;
   @observable int size;
   @observable String valueAsString;  // If primitive.
+  @observable bool valueAsStringIsTruncated;
   @observable ServiceFunction closureFunc;  // If a closure.
   @observable Context closureCtxt;  // If a closure.
   @observable String name;  // If a Type.
   @observable int length; // If a List.
 
   @observable var typeClass;
   @observable var fields;
   @observable var nativeFields;
   @observable var elements;
   @observable var userName;
   @observable var referent;  // If a MirrorReference.
   @observable Instance key;  // If a WeakProperty.
   @observable Instance value;  // If a WeakProperty.
 
   bool get isClosure => closureFunc != null;
 
   Instance._empty(ServiceObjectOwner owner) : super._empty(owner);
 
   void _update(ObservableMap map, bool mapIsRef) {
     // Extract full properties.
     _upgradeCollection(map, isolate);
 
     clazz = map['class'];
     size = map['size'];
     valueAsString = map['valueAsString'];
+    valueAsStringIsTruncated = map['valueAsStringIsTruncated'];
     closureFunc = map['closureFunc'];
     closureCtxt = map['closureCtxt'];
     name = map['name'];
     length = map['length'];
 
     if (mapIsRef) {
       return;
     }
 
     nativeFields = map['nativeFields'];
@@ skipping 1011 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);
     }
   }
 }