Revert r19897, r19898 for breaking mac-64 debug.

src/heap.cc

 // 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 4067 matching lines @@
   ASSERT(!isolate_->code_range()->exists() ||
       isolate_->code_range()->contains(code->address()));
   code->set_instruction_size(desc.instr_size);
   code->set_relocation_info(reloc_info);
   code->set_flags(flags);
   code->set_raw_kind_specific_flags1(0);
   code->set_raw_kind_specific_flags2(0);
   code->set_is_crankshafted(crankshafted);
   code->set_deoptimization_data(empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->set_raw_type_feedback_info(undefined_value());
-  code->set_next_code_link(undefined_value());
   code->set_handler_table(empty_fixed_array(), SKIP_WRITE_BARRIER);
   code->set_gc_metadata(Smi::FromInt(0));
   code->set_ic_age(global_ic_age_);
   code->set_prologue_offset(prologue_offset);
   if (code->kind() == Code::OPTIMIZED_FUNCTION) {
     code->set_marked_for_deoptimization(false);
   }
   code->set_constant_pool(empty_constant_pool_array());
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
@@ skipping 3616 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   OS::MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   OS::MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal