A change in the way we place TransitionElementKinds in the tree.

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 4684 matching lines @@
   static Code* GetCodeAgeStub(Age age, MarkingParity parity);
 
   // Code aging -- platform-specific
   static void PatchPlatformCodeAge(byte* sequence, Age age,
                                    MarkingParity parity);
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(Code);
 };
 
 
+Map* FindClosestElementsTransition(Map* map, ElementsKind to_kind);
+
+
 // All heap objects have a Map that describes their structure.
 //  A Map contains information about:
 //  - Size information about the object
 //  - How to iterate over an object (for garbage collection)
 class Map: public HeapObject {
  public:
   // Instance size.
   // Size in bytes or kVariableSizeSentinel if instances do not have
   // a fixed size.
   inline int instance_size();
@@ skipping 158 matching lines @@
   inline bool HasTransitionArray();
   inline bool HasElementsTransition();
   inline Map* elements_transition_map();
   MUST_USE_RESULT inline MaybeObject* set_elements_transition_map(
       Map* transitioned_map);
   inline void SetTransition(int transition_index, Map* target);
   inline Map* GetTransition(int transition_index);
   MUST_USE_RESULT inline MaybeObject* AddTransition(String* key,
                                                     Map* target,
                                                     SimpleTransitionFlag flag);
+  MaybeObject* AddMissingElementsTransitions(ElementsKind to_kind);
   DECL_ACCESSORS(transitions, TransitionArray)
   inline void ClearTransitions(Heap* heap,
                                WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
   // Tells whether the map is attached to SharedFunctionInfo
   // (for inobject slack tracking).
   inline void set_attached_to_shared_function_info(bool value);
 
   inline bool attached_to_shared_function_info();
 
@@ skipping 221 matching lines @@
   // Returns the map that this map transitions to if its elements_kind
   // is changed to |elements_kind|, or NULL if no such map is cached yet.
   // |safe_to_add_transitions| is set to false if adding transitions is not
   // allowed.
   Map* LookupElementsTransitionMap(ElementsKind elements_kind);
 
   // Returns the transitioned map for this map with the most generic
   // elements_kind that's found in |candidates|, or null handle if no match is
   // found at all.
   Handle<Map> FindTransitionedMap(MapHandleList* candidates);
-  Map* FindTransitionedMap(MapList* candidates);
 
   // Zaps the contents of backing data structures. Note that the
   // heap verifier (i.e. VerifyMarkingVisitor) relies on zapping of objects
   // holding weak references when incremental marking is used, because it also
   // iterates over objects that are otherwise unreachable.
   // In general we only want to call these functions in release mode when
   // heap verification is turned on.
   void ZapPrototypeTransitions();
   void ZapTransitions();
 
@@ skipping 3951 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_