Do not try to serialize VM objects, these are read only canonical objects and should be referred to…

vm/dart_api_message.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_DART_API_MESSAGE_H_
 #define VM_DART_API_MESSAGE_H_
 
 #include "vm/dart_api_state.h"
 #include "vm/snapshot.h"
 
@@ skipping 66 matching lines @@
   // Allocates a backwards reference node.
   BackRefNode* AllocateBackRefNode(Dart_CObject* ref, DeserializeState state);
 
   void Init();
 
   intptr_t LookupInternalClass(intptr_t class_header);
   Dart_CObject* ReadInternalVMObject(intptr_t class_id, intptr_t object_id);
   Dart_CObject* ReadInlinedObject(intptr_t object_id);
   Dart_CObject* ReadObjectImpl();
   Dart_CObject* ReadIndexedObject(intptr_t object_id);
+  Dart_CObject* ReadVMSymbol(intptr_t object_id);
   Dart_CObject* ReadObjectRef();
   Dart_CObject* ReadObject();
 
   // Add object to backward references.
   void AddBackRef(intptr_t id, Dart_CObject* obj, DeserializeState state);
 
   // Get an object from the backward references list.
   Dart_CObject* GetBackRef(intptr_t id);
 
   Dart_CObject_Internal* AsInternal(Dart_CObject* object) {
@@ skipping 39 matching lines @@
   static const intptr_t kDartCObjectMarkOffset = 1;
 
   void MarkCObject(Dart_CObject* object, intptr_t object_id);
   void UnmarkCObject(Dart_CObject* object);
   bool IsCObjectMarked(Dart_CObject* object);
   intptr_t GetMarkedCObjectMark(Dart_CObject* object);
   void UnmarkAllCObjects(Dart_CObject* object);
   void AddToForwardList(Dart_CObject* object);
 
   void WriteSmi(int64_t value);
+  void WriteNullObject();
   void WriteMint(Dart_CObject* object, int64_t value);
   void WriteInt32(Dart_CObject* object);
   void WriteInt64(Dart_CObject* object);
   void WriteInlinedHeader(Dart_CObject* object);
   void WriteCObject(Dart_CObject* object);
   void WriteCObjectRef(Dart_CObject* object);
   void WriteForwardedCObject(Dart_CObject* object);
   void WriteCObjectInlined(Dart_CObject* object, Dart_CObject::Type type);
 
   intptr_t object_id_;
   Dart_CObject** forward_list_;
   intptr_t forward_list_length_;
   intptr_t forward_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ApiMessageWriter);
 };
 
 }  // namespace dart
 
 #endif  // VM_DART_API_MESSAGE_H_