[presubmit] Enable readability/namespace linter checking.

src/scanner.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.
 
 // Features shared by parsing and pre-parsing scanners.
 
 #ifndef V8_SCANNER_H_
 #define V8_SCANNER_H_
 
 #include "src/allocation.h"
@@ skipping 745 matching lines @@
 
   // Whether there is a line terminator whitespace character after
   // the current token, and  before the next. Does not count newlines
   // inside multiline comments.
   bool has_line_terminator_before_next_;
   // Whether there is a multi-line comment that contains a
   // line-terminator after the current token, and before the next.
   bool has_multiline_comment_before_next_;
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_SCANNER_H_