[presubmit] Enable readability/namespace linter checking.

src/dateparser-inl.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_DATEPARSER_INL_H_
 #define V8_DATEPARSER_INL_H_
 
 #include "src/char-predicates-inl.h"
 #include "src/dateparser.h"
 #include "src/unicode-cache-inl.h"
@@ skipping 309 matching lines @@
       }
     }
     if (!scanner->Peek().IsEndOfInput()) return DateToken::Invalid();
   }
   // Successfully parsed ES6 Date Time String.
   day->set_iso_date();
   return DateToken::EndOfInput();
 }
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_DATEPARSER_INL_H_