Properly load transition target descriptor info

src/objects.cc

 // Copyright 2013 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 3862 matching lines @@
           if (!value->FitsRepresentation(representation)) {
             MaybeObject* maybe_map = transition_map->GeneralizeRepresentation(
                 descriptor, value->OptimalRepresentation());
             if (!maybe_map->To(&transition_map)) return maybe_map;
             Object* back = transition_map->GetBackPointer();
             if (back->IsMap()) {
               MaybeObject* maybe_failure =
                   lookup->holder()->MigrateToMap(Map::cast(back));
               if (maybe_failure->IsFailure()) return maybe_failure;
             }
-            DescriptorArray* desc = transition_map->instance_descriptors();
-            int descriptor = transition_map->LastAdded();
-            representation = desc->GetDetails(descriptor).representation();
+            descriptors = transition_map->instance_descriptors();
+            representation =
+                descriptors->GetDetails(descriptor).representation();
           }
           int field_index = descriptors->GetFieldIndex(descriptor);
           result = lookup->holder()->AddFastPropertyUsingMap(
               transition_map, *name, *value, field_index, representation);
         } else {
           result = lookup->holder()->ConvertDescriptorToField(
               *name, *value, attributes);
         }
       } else if (details.type() == CALLBACKS) {
         result = lookup->holder()->ConvertDescriptorToField(
@@ skipping 182 matching lines @@
               value->OptimalRepresentation(value_type);
           if (!value_representation.fits_into(representation)) {
             MaybeObject* maybe_map = transition_map->GeneralizeRepresentation(
                 descriptor, value_representation);
             if (!maybe_map->To(&transition_map)) return maybe_map;
             Object* back = transition_map->GetBackPointer();
             if (back->IsMap()) {
               MaybeObject* maybe_failure = self->MigrateToMap(Map::cast(back));
               if (maybe_failure->IsFailure()) return maybe_failure;
             }
-            DescriptorArray* desc = transition_map->instance_descriptors();
-            int descriptor = transition_map->LastAdded();
-            representation = desc->GetDetails(descriptor).representation();
+            descriptors = transition_map->instance_descriptors();
+            representation =
+                descriptors->GetDetails(descriptor).representation();
           }
           int field_index = descriptors->GetFieldIndex(descriptor);
           result = self->AddFastPropertyUsingMap(
               transition_map, *name, *value, field_index, representation);
         } else {
           result = self->ConvertDescriptorToField(*name, *value, attributes);
         }
       } else if (details.type() == CALLBACKS) {
         result = self->ConvertDescriptorToField(*name, *value, attributes);
       } else {
@@ skipping 11723 matching lines @@
   return static_cast<Type*>(type_raw());
 }
 
 
 void PropertyCell::set_type(Type* type, WriteBarrierMode ignored) {
   set_type_raw(type, ignored);
 }
 
 
 } }  // namespace v8::internal