Fix traversal of the map transition tree to take the prototype

src/objects.h

 // Copyright 2011 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 3843 matching lines @@
   // [prototype transitions]: cache of prototype transitions.
   // Prototype transition is a transition that happens
   // when we change object's prototype to a new one.
   // Cache format:
   //    0: finger - index of the first free cell in the cache
   //    1 + 2 * i: prototype
   //    2 + 2 * i: target map
   DECL_ACCESSORS(prototype_transitions, FixedArray)
   inline FixedArray* unchecked_prototype_transitions();
 
+  static const int kProtoTransitionHeaderSize = 1;
+  static const int kProtoTransitionNumberOfEntriesOffset = 0;
+  static const int kProtoTransitionElementsPerEntry = 2;
+  static const int kProtoTransitionPrototypeOffset = 0;
+  static const int kProtoTransitionMapOffset = 1;
+
+  inline int NumberOfProtoTransitions() {
+    FixedArray* cache = unchecked_prototype_transitions();
+    if (cache->length() == 0) return 0;
+    return
+        Smi::cast(cache->get(kProtoTransitionNumberOfEntriesOffset))->value();
+  }
+
+  inline void SetNumberOfProtoTransitions(int value) {
+    FixedArray* cache = unchecked_prototype_transitions();
+    ASSERT(cache->length() != 0);
+    cache->set_unchecked(kProtoTransitionNumberOfEntriesOffset,
+                         Smi::FromInt(value));
+  }
+
   // Lookup in the map's instance descriptors and fill out the result
   // with the given holder if the name is found. The holder may be
   // NULL when this function is used from the compiler.
   void LookupInDescriptors(JSObject* holder,
                            String* name,
                            LookupResult* result);
 
   MUST_USE_RESULT MaybeObject* CopyDropDescriptors();
 
   MUST_USE_RESULT MaybeObject* CopyNormalized(PropertyNormalizationMode mode,
@@ skipping 3019 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_