Ensure JSProxy correctness for PrototypeIterator uses

src/ic/ic.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ic/ic.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/base/bits.h"
@@ skipping 2237 matching lines @@
         // prototype chain does have dictionary elements. This ensures that
         // other non-dictionary receivers in the polymorphic case benefit
         // from fast path keyed stores.
         if (!old_receiver_map->DictionaryElementsInPrototypeChainOnly()) {
           stub = StoreElementStub(old_receiver_map, store_mode);
 
           // Validate that the store_mode in the stub can also be derived
           // from peeking in the code bits of the handlers.
           if (!FLAG_vector_stores) ValidateStoreMode(stub);
         } else {
-          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "dictionary prototype");
+          TRACE_GENERIC_IC(isolate(), "KeyedStoreIC",
+                           "dictionary or proxy prototype");
         }
       } else {
         TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "non-smi-like key");
       }
     } else {
       TRACE_GENERIC_IC(isolate(), "KeyedStoreIC", "non-JSObject receiver");
     }
   }
 
   if (FLAG_vector_stores) {
@@ skipping 875 matching lines @@
     KeyedLoadICNexus nexus(vector, vector_slot);
     KeyedLoadIC ic(IC::EXTRA_CALL_FRAME, isolate, &nexus);
     ic.UpdateState(receiver, key);
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result, ic.Load(receiver, key));
   }
 
   return *result;
 }
 }  // namespace internal
 }  // namespace v8