Only use the non-strict-arguments-stub if the store site is non-strict.

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 1671 matching lines @@
     }
 
     if (use_ic) {
       ASSERT(!object->IsJSGlobalProxy());
 
       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();
+          if (strict_mode() == kNonStrictMode) {
+            stub = non_strict_arguments_stub();
+          }
         } else if (key_is_smi_like &&
                    !(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);
@@ skipping 1108 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal