[presubmit] Enable readability/namespace linter checking.

src/mips64/lithium-codegen-mips64.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_MIPS_LITHIUM_CODEGEN_MIPS_H_
 #define V8_MIPS_LITHIUM_CODEGEN_MIPS_H_
 
 #include "src/deoptimizer.h"
 #include "src/lithium-codegen.h"
 #include "src/mips64/lithium-gap-resolver-mips64.h"
@@ skipping 411 matching lines @@
   MacroAssembler* masm() const { return codegen_->masm(); }
 
  private:
   LCodeGen* codegen_;
   Label entry_;
   Label exit_;
   Label* external_exit_;
   int instruction_index_;
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_MIPS_LITHIUM_CODEGEN_MIPS_H_