[presubmit] Enable readability/namespace linter checking.

src/arm64/utils-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_UTILS_ARM64_H_
 #define V8_ARM64_UTILS_ARM64_H_
 
 #include <cmath>
 
 #include "src/arm64/constants-arm64.h"
@@ skipping 133 matching lines @@
 // Fused multiply-add.
 inline double FusedMultiplyAdd(double op1, double op2, double a) {
   return fma(op1, op2, a);
 }
 
 
 inline float FusedMultiplyAdd(float op1, float op2, float a) {
   return fmaf(op1, op2, a);
 }
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_ARM64_UTILS_ARM64_H_