[presubmit] Enable readability/namespace linter checking.

src/hydrogen-check-elimination.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_HYDROGEN_CHECK_ELIMINATION_H_
 #define V8_HYDROGEN_CHECK_ELIMINATION_H_
 
 #include "src/hydrogen.h"
 #include "src/hydrogen-alias-analysis.h"
 
@@ skipping 50 matching lines @@
   int narrowed_;
   int loads_;
   int empty_;
   int compares_true_;
   int compares_false_;
   int transitions_;
 #endif
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_HYDROGEN_CHECK_ELIMINATION_H_