Add prototype transitions cache to Map.

src/heap.cc

 // 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 1576 matching lines @@
   map->set_instance_type(instance_type);
   map->set_visitor_id(
       StaticVisitorBase::GetVisitorId(instance_type, instance_size));
   map->set_prototype(null_value());
   map->set_constructor(null_value());
   map->set_instance_size(instance_size);
   map->set_inobject_properties(0);
   map->set_pre_allocated_property_fields(0);
   map->set_instance_descriptors(empty_descriptor_array());
   map->set_code_cache(empty_fixed_array());
+  map->set_prototype_transitions(empty_fixed_array());
   map->set_unused_property_fields(0);
   map->set_bit_field(0);
   map->set_bit_field2((1 << Map::kIsExtensible) | (1 << Map::kHasFastElements));
 
   // If the map object is aligned fill the padding area with Smi 0 objects.
   if (Map::kPadStart < Map::kSize) {
     memset(reinterpret_cast<byte*>(map) + Map::kPadStart - kHeapObjectTag,
            0,
            Map::kSize - Map::kPadStart);
   }
@@ skipping 72 matching lines @@
 
   // Allocate the empty descriptor array.
   { MaybeObject* maybe_obj = AllocateEmptyFixedArray();
     if (!maybe_obj->ToObject(&obj)) return false;
   }
   set_empty_descriptor_array(DescriptorArray::cast(obj));
 
   // Fix the instance_descriptors for the existing maps.
   meta_map()->set_instance_descriptors(empty_descriptor_array());
   meta_map()->set_code_cache(empty_fixed_array());
+  meta_map()->set_prototype_transitions(empty_fixed_array());
 
   fixed_array_map()->set_instance_descriptors(empty_descriptor_array());
   fixed_array_map()->set_code_cache(empty_fixed_array());
+  fixed_array_map()->set_prototype_transitions(empty_fixed_array());
 
   oddball_map()->set_instance_descriptors(empty_descriptor_array());
   oddball_map()->set_code_cache(empty_fixed_array());
+  oddball_map()->set_prototype_transitions(empty_fixed_array());
 
   // Fix prototype object for existing maps.
   meta_map()->set_prototype(null_value());
   meta_map()->set_constructor(null_value());
 
   fixed_array_map()->set_prototype(null_value());
   fixed_array_map()->set_constructor(null_value());
 
   oddball_map()->set_prototype(null_value());
   oddball_map()->set_constructor(null_value());
@@ skipping 4150 matching lines @@
 }
 
 
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 } }  // namespace v8::internal