[presubmit] Enable readability/namespace linter checking.

src/field-index-inl.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_FIELD_INDEX_INL_H_
 #define V8_FIELD_INDEX_INL_H_
 
 #include "src/field-index.h"
 
 namespace v8 {
@@ skipping 100 matching lines @@
 
 inline int FieldIndex::GetKeyedLookupCacheIndex() const {
   if (FLAG_compiled_keyed_generic_loads) {
     return GetLoadByFieldIndex();
   } else {
     return property_index();
   }
 }
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif