[presubmit] Enable readability/namespace linter checking.

src/ia32/codegen-ia32.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_IA32_CODEGEN_IA32_H_
 #define V8_IA32_CODEGEN_IA32_H_
 
 #include "src/ast.h"
 #include "src/macro-assembler.h"
 
@@ skipping 24 matching lines @@
                           XMMRegister input,
                           XMMRegister result,
                           XMMRegister double_scratch,
                           Register temp1,
                           Register temp2);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MathExpGenerator);
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_IA32_CODEGEN_IA32_H_