Introduce LookupIterator::PropertyOrElement which converts name to index if possible.

src/json-stringifier.h

 // 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.
 
 #ifndef V8_JSON_STRINGIFIER_H_
 #define V8_JSON_STRINGIFIER_H_
 
 #include "src/v8.h"
 
 #include "src/conversions.h"
@@ skipping 562 matching lines @@
     for (int i = 0; i < contents->length(); i++) {
       Object* key = contents->get(i);
       Handle<String> key_handle;
       MaybeHandle<Object> maybe_property;
       if (key->IsString()) {
         key_handle = Handle<String>(String::cast(key), isolate_);
         maybe_property = Object::GetPropertyOrElement(object, key_handle);
       } else {
         DCHECK(key->IsNumber());
         key_handle = factory()->NumberToString(Handle<Object>(key, isolate_));
-        uint32_t index;
         if (key->IsSmi()) {
           maybe_property = Object::GetElement(
               isolate_, object, Smi::cast(key)->value());
-        } else if (key_handle->AsArrayIndex(&index)) {
-          maybe_property = Object::GetElement(isolate_, object, index);
         } else {
           maybe_property = Object::GetPropertyOrElement(object, key_handle);
         }
       }
       Handle<Object> property;
       ASSIGN_RETURN_ON_EXCEPTION_VALUE(
           isolate_, property, maybe_property, EXCEPTION);
       Result result = SerializeProperty(property, comma, key_handle);
       if (!comma && result == SUCCESS) comma = true;
       if (result == EXCEPTION) return result;
@@ skipping 82 matching lines @@
       SerializeString_<uint8_t, uc16>(object);
     } else {
       SerializeString_<uc16, uc16>(object);
     }
   }
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSON_STRINGIFIER_H_