[presubmit] Enable readability/namespace linter checking.

src/lookup-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_LOOKUP_INL_H_
 #define V8_LOOKUP_INL_H_
 
 #include "src/lookup.h"
 
 #include "src/elements.h"
@@ skipping 118 matching lines @@
           !SkipInterceptor(JSObject::cast(holder))) {
         return INTERCEPTOR;
       }
     // Fall through.
     default:
       return NOT_FOUND;
   }
   UNREACHABLE();
   return state_;
 }
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_LOOKUP_INL_H_