Prepare GetProperty(Attributes)WithInterceptor to support elements

src/lookup.h

 // Copyright 2014 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_LOOKUP_H_
 #define V8_LOOKUP_H_
 
 #include "src/factory.h"
 #include "src/isolate.h"
 #include "src/objects.h"
@@ skipping 108 matching lines @@
         initial_holder_(holder_),
         number_(DescriptorArray::kNotFound) {
     // kMaxUInt32 isn't a valid index.
     DCHECK_NE(kMaxUInt32, index_);
     Next();
   }
 
   Isolate* isolate() const { return isolate_; }
   State state() const { return state_; }
 
-  Handle<Name> name() const { return name_; }
+  Handle<Name> name() const {
+    DCHECK(!IsElement());
+    return name_;
+  }
+  Handle<Name> GetName() {
+    if (name_.is_null()) {
+      DCHECK(IsElement());
+      name_ = isolate_->factory()->Uint32ToString(index_);
+    }
+    return name_;
+  }
   uint32_t index() const { return index_; }
 
   bool IsElement() const { return index_ != kMaxUInt32; }
 
   bool IsFound() const { return state_ != NOT_FOUND; }
   void Next();
   void NotFound() {
     has_property_ = false;
     state_ = NOT_FOUND;
   }
@@ skipping 122 matching lines @@
   Handle<JSReceiver> holder_;
   Handle<Map> holder_map_;
   const Handle<JSReceiver> initial_holder_;
   uint32_t number_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LOOKUP_H_