Directly store the transition target on LookupResult in TransitionResult.

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 6065 matching lines @@
   // with the given holder if the name is found. The holder may be
   // NULL when this function is used from the compiler.
   inline void LookupDescriptor(JSObject* holder,
                                Name* name,
                                LookupResult* result);
 
   inline void LookupTransition(JSObject* holder,
                                Name* name,
                                LookupResult* result);
 
+  inline PropertyDetails GetLastDescriptorDetails();
+
   // The size of transition arrays are limited so they do not end up in large
   // object space. Otherwise ClearNonLiveTransitions would leak memory while
   // applying in-place right trimming.
   inline bool CanHaveMoreTransitions();
 
   int LastAdded() {
     int number_of_own_descriptors = NumberOfOwnDescriptors();
     ASSERT(number_of_own_descriptors > 0);
     return number_of_own_descriptors - 1;
   }
@@ skipping 4662 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_