Correct handling of arrays with callbacks in the prototype chain.

src/ic.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 1958 matching lines @@
       ASSERT(!object->IsJSGlobalProxy());
 
       if (miss_mode != MISS_FORCE_GENERIC) {
         if (object->IsJSObject()) {
           Handle<JSObject> receiver = Handle<JSObject>::cast(object);
           bool key_is_smi_like = key->IsSmi() || !key->ToSmi()->IsFailure();
           if (receiver->elements()->map() ==
               isolate()->heap()->non_strict_arguments_elements_map()) {
             stub = non_strict_arguments_stub();
           } else if (key_is_smi_like &&
-                     (!target().is_identical_to(non_strict_arguments_stub()))) {
-            KeyedAccessStoreMode store_mode =
-                GetStoreMode(receiver, key, value);
-            stub = StoreElementStub(receiver, store_mode);
+                     !(target().is_identical_to(non_strict_arguments_stub()))) {
+            // We should go generic if receiver isn't a dictionary, but our
+            // prototype chain does have dictionary elements. This ensures that
+            // other non-dictionary receivers in the polymorphic case benefit
+            // from fast path keyed stores.
+            if (!(receiver->map()->DictionaryElementsInPrototypeChainOnly())) {
+              KeyedAccessStoreMode store_mode =
+                  GetStoreMode(receiver, key, value);
+              stub = StoreElementStub(receiver, store_mode);
+            }
           }
         }
       }
     }
   }
 
   if (!is_target_set()) {
     if (*stub == *generic_stub()) {
       TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "set generic");
     }
@@ skipping 270 matching lines @@
   ic.UpdateState(receiver, key);
   return ic.Store(receiver, key, args.at<Object>(2), MISS_FORCE_GENERIC);
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, ElementsTransitionAndStoreIC_Miss) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 4);
   KeyedStoreIC ic(IC::EXTRA_CALL_FRAME, isolate);
   Handle<Object> value = args.at<Object>(0);
+  Handle<Map> map = args.at<Map>(1);
   Handle<Object> key = args.at<Object>(2);
   Handle<Object> object = args.at<Object>(3);
   StrictModeFlag strict_mode = ic.strict_mode();
+  if (object->IsJSObject()) {
+    JSObject::TransitionElementsKind(Handle<JSObject>::cast(object),
+                                     map->elements_kind());
+  }
   return Runtime::SetObjectProperty(isolate,
                                     object,
                                     key,
                                     value,
                                     NONE,
                                     strict_mode);
 }
 
 
 const char* BinaryOpIC::GetName(TypeInfo type_info) {
@@ skipping 440 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal