[presubmit] Enable readability/namespace linter checking.

src/lithium-codegen.h

 // Copyright 2013 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_LITHIUM_CODEGEN_H_
 #define V8_LITHIUM_CODEGEN_H_
 
 #include "src/bailout-reason.h"
 #include "src/compiler.h"
 #include "src/deoptimizer.h"
@@ skipping 73 matching lines @@
 
   void Abort(BailoutReason reason);
   void Retry(BailoutReason reason);
 
   // Methods for code dependencies.
   void AddDeprecationDependency(Handle<Map> map);
   void AddStabilityDependency(Handle<Map> map);
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_LITHIUM_CODEGEN_H_