[presubmit] Enable readability/namespace linter checking.

src/version.h

 // Copyright 2009 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_VERSION_H_
 #define V8_VERSION_H_
 
 #include "src/base/functional.h"
 #include "src/vector.h"
 
@@ skipping 29 matching lines @@
   static int patch_;
   static bool candidate_;
   static const char* soname_;
   static const char* version_string_;
 
   // In test-version.cc.
   friend void SetVersion(int major, int minor, int build, int patch,
                          bool candidate, const char* soname);
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_VERSION_H_