[presubmit] Enable readability/namespace linter checking.

src/ast.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_AST_H_
 #define V8_AST_H_
 
 #include "src/assembler.h"
 #include "src/ast-value-factory.h"
 #include "src/bailout-reason.h"
@@ skipping 3604 matching lines @@
   // inspected.
   // See ParseFunctionLiteral in parser.cc for preconditions.
   Zone* local_zone_;
   // ZoneObjects which need to persist until scope analysis must be allocated in
   // the parser-level zone.
   Zone* parser_zone_;
   AstValueFactory* ast_value_factory_;
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_AST_H_