[presubmit] Enable readability/namespace linter checking.

src/arm64/disasm-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_DISASM_ARM64_H
 #define V8_ARM64_DISASM_ARM64_H
 
 #include "src/arm64/decoder-arm64.h"
 #include "src/arm64/instructions-arm64.h"
 #include "src/globals.h"
@@ skipping 67 matching lines @@
   explicit PrintDisassembler(FILE* stream) : stream_(stream) { }
   ~PrintDisassembler() { }
 
   virtual void ProcessOutput(Instruction* instr);
 
  private:
   FILE *stream_;
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_ARM64_DISASM_ARM64_H