Add a verification step which iterates over the heap and verifies that all canonical objects are co…

runtime/vm/raw_object_snapshot.cc

 // 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.
 
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
@@ skipping 213 matching lines @@
                         bool as_reference) {
   ASSERT(reader != NULL);
 
   // Determine if the type class of this type is in the full snapshot.
   bool typeclass_is_in_fullsnapshot = reader->Read<bool>();
 
   // Allocate type object.
   Type& type = Type::ZoneHandle(reader->zone(), NEW_OBJECT(Type));
   bool is_canonical = RawObject::IsCanonical(tags);
   bool defer_canonicalization = is_canonical &&
-      (!Snapshot::IsFull(kind) && typeclass_is_in_fullsnapshot);
+      ((kind == Snapshot::kMessage) ||
+       (!Snapshot::IsFull(kind) && typeclass_is_in_fullsnapshot));
   reader->AddBackRef(object_id, &type, kIsDeserialized, defer_canonicalization);
 
   // Set all non object fields.
   type.set_token_pos(TokenPosition::SnapshotDecode(reader->Read<int32_t>()));
   type.set_type_state(reader->Read<int8_t>());
 
   // Set all the object fields.
   READ_OBJECT_FIELDS(type, type.raw()->from(), type.raw()->to(), kAsReference);
 
   // Read in the type class.
@@ skipping 3074 matching lines @@
     // We do not allow objects with native fields in an isolate message.
     writer->SetWriteException(Exceptions::kArgument,
                               "Illegal argument in isolate message"
                               " : (object is a UserTag)");
   } else {
     UNREACHABLE();
   }
 }
 
 }  // namespace dart