[presubmit] Enable readability/namespace linter checking.

src/arm/constants-arm.h

 // Copyright 2011 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_ARM_CONSTANTS_ARM_H_
 #define V8_ARM_CONSTANTS_ARM_H_
 
 #include <stdint.h>
 
 #include "src/base/logging.h"
@@ skipping 684 matching lines @@
   // Lookup the register number for the name provided.
   // Set flag pointed by is_double to true if register
   // is double-precision.
   static int Number(const char* name, bool* is_double);
 
  private:
   static const char* names_[kNumVFPRegisters];
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_ARM_CONSTANTS_ARM_H_