Fix slack tracking when instance prototype changes.

src/objects-inl.h

 // 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 4395 matching lines @@
 Map* JSFunction::initial_map() {
   return Map::cast(prototype_or_initial_map());
 }
 
 
 void JSFunction::set_initial_map(Map* value) {
   set_prototype_or_initial_map(value);
 }
 
 
-MaybeObject* JSFunction::set_initial_map_and_cache_transitions(
-    Map* initial_map) {
-  Context* native_context = context()->native_context();
-  Object* array_function =
-      native_context->get(Context::ARRAY_FUNCTION_INDEX);
-  if (array_function->IsJSFunction() &&
-      this == JSFunction::cast(array_function)) {
-    // Replace all of the cached initial array maps in the native context with
-    // the appropriate transitioned elements kind maps.
-    Heap* heap = GetHeap();
-    MaybeObject* maybe_maps =
-        heap->AllocateFixedArrayWithHoles(kElementsKindCount);
-    FixedArray* maps;
-    if (!maybe_maps->To(&maps)) return maybe_maps;
-
-    Map* current_map = initial_map;
-    ElementsKind kind = current_map->elements_kind();
-    ASSERT(kind == GetInitialFastElementsKind());
-    maps->set(kind, current_map);
-    for (int i = GetSequenceIndexFromFastElementsKind(kind) + 1;
-         i < kFastElementsKindCount; ++i) {
-      Map* new_map;
-      ElementsKind next_kind = GetFastElementsKindFromSequenceIndex(i);
-      MaybeObject* maybe_new_map =
-          current_map->CopyAsElementsKind(next_kind, INSERT_TRANSITION);
-      if (!maybe_new_map->To(&new_map)) return maybe_new_map;
-      maps->set(next_kind, new_map);
-      current_map = new_map;
-    }
-    native_context->set_js_array_maps(maps);
-  }
-  set_initial_map(initial_map);
-  return this;
-}
-
-
 bool JSFunction::has_initial_map() {
   return prototype_or_initial_map()->IsMap();
 }
 
 
 bool JSFunction::has_instance_prototype() {
   return has_initial_map() || !prototype_or_initial_map()->IsTheHole();
 }
 
 
@@ skipping 1079 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_