Store builtin index on the builtin code object.

src/objects.h

 // Copyright 2012 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.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
 #include "src/builtins.h"
@@ skipping 5590 matching lines @@
   // level of loop nesting we are willing to do on-stack replacement
   // for.
   inline void set_allow_osr_at_loop_nesting_level(int level);
   inline int allow_osr_at_loop_nesting_level();
 
   // [profiler_ticks]: For FUNCTION kind, tells for how many profiler ticks
   // the code object was seen on the stack with no IC patching going on.
   inline int profiler_ticks();
   inline void set_profiler_ticks(int ticks);
 
+  // [builtin_index]: For BUILTIN kind, tells which builtin index it has.
+  inline int builtin_index();
+  inline void set_builtin_index(int id);
+
   // [stack_slots]: For kind OPTIMIZED_FUNCTION, the number of stack slots
   // reserved in the code prologue.
   inline unsigned stack_slots();
   inline void set_stack_slots(unsigned slots);
 
   // [safepoint_table_start]: For kind OPTIMIZED_CODE, the offset in
   // the instruction stream where the safepoint table starts.
   inline unsigned safepoint_table_offset();
   inline void set_safepoint_table_offset(unsigned offset);
 
@@ skipping 5606 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_