Only count the descriptor array if it's owned by the map.

src/mark-compact.cc

 // 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 1530 matching lines @@
 
 template<>
 class MarkCompactMarkingVisitor::ObjectStatsTracker<
     MarkCompactMarkingVisitor::kVisitMap> {
  public:
   static inline void Visit(Map* map, HeapObject* obj) {
     Heap* heap = map->GetHeap();
     Map* map_obj = Map::cast(obj);
     ASSERT(map->instance_type() == MAP_TYPE);
     DescriptorArray* array = map_obj->instance_descriptors();
-    if (array != heap->empty_descriptor_array()) {
+    if (map_obj->owns_descriptors() &&
+        array != heap->empty_descriptor_array()) {
       int fixed_array_size = array->Size();
       heap->RecordObjectStats(FIXED_ARRAY_TYPE,
                               DESCRIPTOR_ARRAY_SUB_TYPE,
                               fixed_array_size);
     }
     if (map_obj->HasTransitionArray()) {
       int fixed_array_size = map_obj->transitions()->Size();
       heap->RecordObjectStats(FIXED_ARRAY_TYPE,
                               TRANSITION_ARRAY_SUB_TYPE,
                               fixed_array_size);
@@ skipping 2582 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal