[presubmit] Enable readability/namespace linter checking.

src/i18n.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.
 // limitations under the License.
 
 #ifndef V8_I18N_H_
 #define V8_I18N_H_
 
 #include "src/handles.h"
 #include "unicode/uversion.h"
@@ skipping 110 matching lines @@
 
   // Release memory we allocated for the BreakIterator once the JS object that
   // holds the pointer gets garbage collected.
   static void DeleteBreakIterator(
       const v8::WeakCallbackData<v8::Value, void>& data);
 
  private:
   BreakIterator();
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_I18N_H_