Store entry id as 32-bit int.

src/profile-generator-inl.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 96 matching lines @@
 }
 
 
 int V8HeapExplorer::GetGcSubrootOrder(HeapObject* subroot) {
   return static_cast<int>(
       (reinterpret_cast<char*>(subroot) -
        reinterpret_cast<char*>(kFirstGcSubrootObject)) /
       HeapObjectsMap::kObjectIdStep);
 }
 
-
-SnapshotObjectId HeapEntry::id() {
-  union {
-    Id stored_id;
-    SnapshotObjectId returned_id;
-  } id_adaptor = {id_};
-  return id_adaptor.returned_id;
-}
-
 } }  // namespace v8::internal
 
 #endif  // V8_PROFILE_GENERATOR_INL_H_