[presubmit] Enable readability/namespace linter checking.

src/layout-descriptor.h

 // Copyright 2014 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_LAYOUT_DESCRIPTOR_H_
 #define V8_LAYOUT_DESCRIPTOR_H_
 
 #include <iosfwd>
 
 #include "src/objects.h"
@@ skipping 135 matching lines @@
   // |out_end_of_contiguous_region_offset|. The |end_offset| value is the
   // upper bound for |out_end_of_contiguous_region_offset|.
   bool IsTagged(int offset_in_bytes, int end_offset,
                 int* out_end_of_contiguous_region_offset);
 
  private:
   bool all_fields_tagged_;
   int header_size_;
   LayoutDescriptor* layout_descriptor_;
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_LAYOUT_DESCRIPTOR_H_