Revert r19897, r19898 for breaking mac-64 debug.

src/objects-visiting.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 396 matching lines @@
   INLINE(static void VisitPropertyCell(Map* map, HeapObject* object));
   INLINE(static void VisitAllocationSite(Map* map, HeapObject* object));
   INLINE(static void VisitCodeEntry(Heap* heap, Address entry_address));
   INLINE(static void VisitEmbeddedPointer(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitCell(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitDebugTarget(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitCodeTarget(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitCodeAgeSequence(Heap* heap, RelocInfo* rinfo));
   INLINE(static void VisitExternalReference(RelocInfo* rinfo)) { }
   INLINE(static void VisitRuntimeEntry(RelocInfo* rinfo)) { }
-  // Skip the weak next code link in a code object.
-  INLINE(static void VisitNextCodeLink(Heap* heap, Object** slot)) { }
 
   // TODO(mstarzinger): This should be made protected once refactoring is done.
   // Mark non-optimize code for functions inlined into the given optimized
   // code. This will prevent it from being flushed.
   static void MarkInlinedFunctionsCode(Heap* heap, Code* code);
 
  protected:
   INLINE(static void VisitMap(Map* map, HeapObject* object));
   INLINE(static void VisitCode(Map* map, HeapObject* object));
   INLINE(static void VisitSharedFunctionInfo(Map* map, HeapObject* object));
@@ skipping 50 matching lines @@
 
 
 template<typename StaticVisitor>
 VisitorDispatchTable<typename StaticMarkingVisitor<StaticVisitor>::Callback>
     StaticMarkingVisitor<StaticVisitor>::table_;
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_VISITING_H_