[presubmit] Enable readability/namespace linter checking.

src/date.h

 // Copyright 2012 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_DATE_H_
 #define V8_DATE_H_
 
 #include "src/allocation.h"
 #include "src/base/platform/platform.h"
 #include "src/globals.h"
@@ skipping 258 matching lines @@
   // Year/Month/Day cache.
   bool ymd_valid_;
   int ymd_days_;
   int ymd_year_;
   int ymd_month_;
   int ymd_day_;
 
   base::TimezoneCache* tz_cache_;
 };
 
-} }   // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif