Optimistically assume that elements IC only transition once.

src/hydrogen.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 5545 matching lines @@
     ASSERT(map->IsMap());
     if (!transition_target.at(i).is_null()) {
       ASSERT(Map::IsValidElementsTransition(
           map->elements_kind(),
           transition_target.at(i)->elements_kind()));
       transition = new(zone()) HTransitionElementsKind(
           object, map, transition_target.at(i));
       AddInstruction(transition);
     } else {
       type_todo[map->elements_kind()] = true;
-      if (map->elements_kind() >= FIRST_EXTERNAL_ARRAY_ELEMENTS_KIND) {
+      if (IsExternalArrayElementsKind(map->elements_kind())) {
         todo_external_array = true;
       }
       num_untransitionable_maps++;
       untransitionable_map = map;
     }
   }
 
   // If only one map is left after transitioning, handle this case
   // monomorphically.
   if (num_untransitionable_maps == 1) {
@@ skipping 3550 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal