[serializer] cosmetic changes to SerializerReference.

src/snapshot/deserializer.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/snapshot/deserializer.h"
 
 #include "src/bootstrapper.h"
 #include "src/external-reference-table.h"
 #include "src/heap/heap.h"
 #include "src/isolate.h"
@@ skipping 294 matching lines @@
     // Assign a new script id to avoid collision.
     script->set_id(isolate_->heap()->NextScriptId());
     // Add script to list.
     Handle<Object> list = WeakFixedArray::Add(factory->script_list(), script);
     heap->SetRootScriptList(*list);
   }
 }
 
 HeapObject* Deserializer::GetBackReferencedObject(int space) {
   HeapObject* obj;
-  SerializerReference back_reference(source_.GetInt());
+  SerializerReference back_reference =
+      SerializerReference::FromBitfield(source_.GetInt());
   if (space == LO_SPACE) {
     CHECK(back_reference.chunk_index() == 0);
     uint32_t index = back_reference.large_object_index();
     obj = deserialized_large_objects_[index];
   } else {
     DCHECK(space < kNumberOfPreallocatedSpaces);
     uint32_t chunk_index = back_reference.chunk_index();
     DCHECK_LE(chunk_index, current_chunk_[space]);
     uint32_t chunk_offset = back_reference.chunk_offset();
     Address address = reservations_[space][chunk_index].start + chunk_offset;
@@ skipping 479 matching lines @@
 
       default:
         CHECK(false);
     }
   }
   CHECK_EQ(limit, current);
   return true;
 }
 }  // namespace internal
 }  // namespace v8