[presubmit] Enable readability/namespace linter checking.

src/arm64/instrument-arm64.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_ARM64_INSTRUMENT_ARM64_H_
 #define V8_ARM64_INSTRUMENT_ARM64_H_
 
 #include "src/globals.h"
 #include "src/utils.h"
 
@@ skipping 62 matching lines @@
 
   void InstrumentLoadStore(Instruction* instr);
   void InstrumentLoadStorePair(Instruction* instr);
 
   std::list<Counter*> counters_;
 
   FILE *output_stream_;
   uint64_t sample_period_;
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_ARM64_INSTRUMENT_ARM64_H_