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

vm/raw_object.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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/token.h"
@@ skipping 1020 matching lines @@
 };
 
 
 class RawOneByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(OneByteString);
 
   // Variable length data follows here.
   uint8_t data_[0];
 
   friend class SnapshotReader;
+  friend class ApiMessageReader;
 };
 
 
 class RawTwoByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(TwoByteString);
 
   // Variable length data follows here.
   uint16_t data_[0];
 
   friend class SnapshotReader;
@@ skipping 467 matching lines @@
          kExternalUint64Array == kByteArray + 18 &&
          kExternalFloat32Array == kByteArray + 19 &&
          kExternalFloat64Array == kByteArray + 20 &&
          kClosure == kByteArray + 21);
   return (index >= kByteArray && index <= kClosure);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_