Store entry id as 32-bit int.

src/profile-generator-inl.h

Index: src/profile-generator-inl.h
diff --git a/src/profile-generator-inl.h b/src/profile-generator-inl.h
index d967ed3897a6a462b91e550cad6419356d568292..65369befdfa8fa710eecf09a2e174f64fec214b2 100644
--- a/src/profile-generator-inl.h
+++ b/src/profile-generator-inl.h
@@ -114,15 +114,6 @@ int V8HeapExplorer::GetGcSubrootOrder(HeapObject* subroot) {
       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_