[presubmit] Enable readability/namespace linter checking.

src/property-details.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_PROPERTY_DETAILS_H_
 #define V8_PROPERTY_DETAILS_H_
 
 #include "include/v8.h"
 #include "src/allocation.h"
 #include "src/utils.h"
@@ skipping 353 matching lines @@
     value_ = AttributesField::update(value, attributes);
   }
 
   uint32_t value_;
 };
 
 
 std::ostream& operator<<(std::ostream& os,
                          const PropertyAttributes& attributes);
 std::ostream& operator<<(std::ostream& os, const PropertyDetails& details);
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_PROPERTY_DETAILS_H_