[presubmit] Enable readability/namespace linter checking.

src/bignum-dtoa.h

 // Copyright 2010 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_BIGNUM_DTOA_H_
 #define V8_BIGNUM_DTOA_H_
 
 #include "src/vector.h"
 
 namespace v8 {
@@ skipping 37 matching lines @@
 //  - PRECISION: produces 'requested_digits' where the first digit is not '0'.
 //   Even though the length of produced digits usually equals
 //   'requested_digits', the function is allowed to return fewer digits, in
 //   which case the caller has to fill the missing digits with '0's.
 //   Halfway cases are again rounded up.
 // 'BignumDtoa' expects the given buffer to be big enough to hold all digits
 // and a terminating null-character.
 void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits,
                 Vector<char> buffer, int* length, int* point);
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_BIGNUM_DTOA_H_