Fix building with clang

src/serialize.h

 // Copyright 2012 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 323 matching lines @@
   explicit Deserializer(SnapshotByteSource* source);
 
   virtual ~Deserializer();
 
   // Deserialize the snapshot into an empty heap.
   void Deserialize();
 
   // Deserialize a single object and the objects reachable from it.
   void DeserializePartial(Object** root);
 
-#ifdef DEBUG
-  virtual void Synchronize(const char* tag);
-#endif
-
  private:
   virtual void VisitPointers(Object** start, Object** end);
 
   virtual void VisitExternalReferences(Address* start, Address* end) {
     UNREACHABLE();
   }
 
   virtual void VisitRuntimeEntry(RelocInfo* rinfo) {
     UNREACHABLE();
   }
@@ skipping 120 matching lines @@
   }
 
   static void Disable() { serialization_enabled_ = false; }
   // Call this when you have made use of the fact that there is no serialization
   // going on.
   static void TooLateToEnableNow() { too_late_to_enable_now_ = true; }
   static bool enabled() { return serialization_enabled_; }
   SerializationAddressMapper* address_mapper() { return &address_mapper_; }
   void PutRoot(
       int index, HeapObject* object, HowToCode how, WhereToPoint where);
-#ifdef DEBUG
-  virtual void Synchronize(const char* tag);
-#endif
 
  protected:
   static const int kInvalidRootIndex = -1;
 
   int RootIndex(HeapObject* heap_object);
   virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) = 0;
   intptr_t root_index_wave_front() { return root_index_wave_front_; }
   void set_root_index_wave_front(intptr_t value) {
     ASSERT(value >= root_index_wave_front_);
     root_index_wave_front_ = value;
@@ skipping 146 matching lines @@
  private:
   virtual bool ShouldBeInThePartialSnapshotCache(HeapObject* o) {
     return false;
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_