Consistently use only one of virtual/OVERRIDE/FINAL.

src/serialize.h

Index: src/serialize.h
diff --git a/src/serialize.h b/src/serialize.h
index c524fcf5d03b18dc6ea47a036f88d92eda7ebdda..0c84ca314ff6fd5d7d401192fbbcb3465eea6125 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -595,7 +595,7 @@ class Serializer : public SerializerDeserializer {
  public:
   Serializer(Isolate* isolate, SnapshotByteSink* sink);
   ~Serializer();
-  virtual void VisitPointers(Object** start, Object** end) OVERRIDE;
+  void VisitPointers(Object** start, Object** end) OVERRIDE;
 
   void EncodeReservations(List<SerializedData::Reservation>* out) const;
 
@@ -780,7 +780,7 @@ class StartupSerializer : public Serializer {
 
   // The StartupSerializer has to serialize the root array, which is slightly
   // different.
-  virtual void VisitPointers(Object** start, Object** end) OVERRIDE;
+  void VisitPointers(Object** start, Object** end) OVERRIDE;
 
   // Serialize the current state of the heap.  The order is:
   // 1) Strong references.