Bugfix: A TransitionArray can disappear during copy.

src/objects.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 6173 matching lines @@
   inline bool HasTransitionArray();
   inline bool HasElementsTransition();
   inline Map* elements_transition_map();
   static Handle<TransitionArray> SetElementsTransitionMap(
       Handle<Map> map, Handle<Map> transitioned_map);
   inline void SetTransition(int transition_index, Map* target);
   inline Map* GetTransition(int transition_index);
   inline int SearchTransition(Name* name);
   inline FixedArrayBase* GetInitialElements();
 
-  static Handle<TransitionArray> AddTransition(Handle<Map> map,
-                                               Handle<Name> key,
-                                               Handle<Map> target,
-                                               SimpleTransitionFlag flag);
   DECL_ACCESSORS(transitions, TransitionArray)
   inline void ClearTransitions(Heap* heap,
                                WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
   void DeprecateTransitionTree();
   void DeprecateTarget(Name* key, DescriptorArray* new_descriptors);
 
   Map* FindRootMap();
   Map* FindUpdatedMap(int verbatim, int length, DescriptorArray* descriptors);
   Map* FindLastMatchMap(int verbatim, int length, DescriptorArray* descriptors);
@@ skipping 4811 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_