Re-land Notifier.prototype.performChange + tests

src/objects.cc

 // Copyright 2013 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 13542 matching lines @@
 // If the object is in dictionary mode, it is converted to fast elements
 // mode.
 MaybeObject* JSObject::PrepareElementsForSort(uint32_t limit) {
   Heap* heap = GetHeap();
 
   if (HasDictionaryElements()) {
     // Convert to fast elements containing only the existing properties.
     // Ordering is irrelevant, since we are going to sort anyway.
     SeededNumberDictionary* dict = element_dictionary();
     if (IsJSArray() || dict->requires_slow_elements() ||
-        dict->max_number_key() >= limit) {
+        dict->max_number_key() >= limit || map()->is_observed()) {
       return PrepareSlowElementsForSort(limit);
     }
     // Convert to fast elements.
 
     Object* obj;
     MaybeObject* maybe_obj = GetElementsTransitionMap(GetIsolate(),
                                                       FAST_HOLEY_ELEMENTS);
     if (!maybe_obj->ToObject(&obj)) return maybe_obj;
     Map* new_map = Map::cast(obj);
 
@@ skipping 1854 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