Remove dead code from LookupResult

src/field-index.cc

-// 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.
-
-#include "src/v8.h"
-
-#include "src/field-index.h"
-#include "src/objects.h"
-#include "src/objects-inl.h"
-
-namespace v8 {
-namespace internal {
-
-
-FieldIndex FieldIndex::ForLookupResult(const LookupResult* lookup_result) {
-  Map* map = lookup_result->holder()->map();
-  return ForPropertyIndex(map,
-                          lookup_result->GetFieldIndexFromMap(map),
-                          lookup_result->representation().IsDouble());
-}
-
-
-} }  // namespace v8::internal