Make sure transitioned arrays efficiently call builtin Array functions

src/objects.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// 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
 //       with the distribution.
@@ skipping 2323 matching lines @@
   if (index == DescriptorLookupCache::kAbsent) {
     index = descriptors->Search(sentinel_name);
     cache->Update(descriptors, sentinel_name, index);
   }
   // If the transition already exists, return its descriptor.
   if (index != DescriptorArray::kNotFound) {
     PropertyDetails details(descriptors->GetDetails(index));
     if (details.type() == ELEMENTS_TRANSITION) {
       return descriptors->GetValue(index);
     } else {
-      *safe_to_add_transition = false;
+      if (safe_to_add_transition != NULL) {
+        *safe_to_add_transition = false;
+      }
     }
   }
   return NULL;
 }
 
 
 Map* Map::LookupElementsTransitionMap(ElementsKind elements_kind,
                                       bool* safe_to_add_transition) {
   // Special case: indirect SMI->FAST transition (cf. comment in
   // AddElementsTransition()).
@@ skipping 10242 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single break point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal