Make sure transitioned arrays efficiently call builtin Array functions

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index a0e77cb86dbd63a8bff729b21e37a57878b8a619..3d077b4a8d78dfab860166f35e40687570387c88 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1,4 +1,4 @@
-// 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:
@@ -162,6 +162,11 @@ enum ElementsKind {
   LAST_ELEMENTS_KIND = EXTERNAL_PIXEL_ELEMENTS
 };
 
+enum CompareMapMode {
+  REQUIRE_EXACT_MAP,
+  ALLOW_ELEMENT_TRANSITION_MAPS
+};
+
 const int kElementsKindCount = LAST_ELEMENTS_KIND - FIRST_ELEMENTS_KIND + 1;
 
 void PrintElementsKind(FILE* out, ElementsKind kind);