Support untagged object pool entries.

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/object.h"
 #include "vm/object_store.h"
 #include "vm/snapshot.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 #include "vm/visitor.h"
@@ skipping 1244 matching lines @@
 
 void RawCode::WriteTo(SnapshotWriter* writer,
                       intptr_t object_id,
                       Snapshot::Kind kind) {
   // We have already checked for this and written a NULL object, hence we
   // should not reach here.
   UNREACHABLE();
 }
 
 
+RawObjectPool* ObjectPool::ReadFrom(SnapshotReader* reader,
+                                    intptr_t object_id,
+                                    intptr_t tags,
+                                    Snapshot::Kind kind) {
+  UNREACHABLE();
+  return ObjectPool::null();
+}
+
+
+void RawObjectPool::WriteTo(SnapshotWriter* writer,
+                            intptr_t object_id,
+                            Snapshot::Kind kind) {
+  UNREACHABLE();
+}
+
+
 RawInstructions* Instructions::ReadFrom(SnapshotReader* reader,
                                         intptr_t object_id,
                                         intptr_t tags,
                                         Snapshot::Kind kind) {
   UNREACHABLE();
   return Instructions::null();
 }
 
 
 void RawInstructions::WriteTo(SnapshotWriter* writer,
@@ skipping 1603 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