Fix CNLT regression.

src/objects.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 5127 matching lines @@
 
   // In case the map did not own its own descriptors, a split is forced by
   // copying the map; creating a new descriptor array cell.
   // Create a new free-floating map only if we are not allowed to store it.
   Map* new_map;
   MaybeObject* maybe_new_map = Copy();
   if (!maybe_new_map->To(&new_map)) return maybe_new_map;
   ASSERT(new_map->NumberOfOwnDescriptors() == NumberOfOwnDescriptors());
   new_map->set_elements_kind(kind);
 
-  if (flag == INSERT_TRANSITION) {
+  if (flag == INSERT_TRANSITION && !HasElementsTransition()) {
     // Map::Copy does not store the descriptor array in case it is empty, since
     // it does not insert a back pointer; implicitly indicating that its
     // descriptor array is empty. Since in this case we do want to insert a back
     // pointer, we have to manually set the empty descriptor array to force a
     // split.
     if (!new_map->StoresOwnDescriptors()) {
       ASSERT(new_map->NumberOfOwnDescriptors() == 0);
       MaybeObject* maybe_failure =
           new_map->SetDescriptors(GetHeap()->empty_descriptor_array());
       if (maybe_failure->IsFailure()) return maybe_failure;
@@ skipping 2398 matching lines @@
   if (descriptors_owner_died) {
     if (number_of_own_descriptors > 0) {
       TrimDescriptorArray(heap, this, descriptors, number_of_own_descriptors);
       ASSERT(descriptors->number_of_descriptors() == number_of_own_descriptors);
     } else {
       t->set_descriptors(heap->empty_descriptor_array());
     }
     set_owns_descriptors(true);
   }
 
-  // If the final transition array does not contain any live transitions, remove
-  // the transition array from the map.
-  if (transition_index == 0 &&
-      !t->HasElementsTransition() &&
-      !t->HasPrototypeTransitions() &&
-      number_of_own_descriptors == 0) {
-    ASSERT(owns_descriptors());
-    return ClearTransitions(heap);
-  }
-
   int trim = t->number_of_transitions() - transition_index;
   if (trim > 0) {
     RightTrimFixedArray<FROM_GC>(heap, t, t->IsSimpleTransition()
         ? trim : trim * TransitionArray::kTransitionSize);
   }
 }
 
 
 int Map::Hash() {
   // For performance reasons we only hash the 3 most variable fields of a map:
@@ skipping 5963 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal