[presubmit] Enable readability/namespace linter checking.

src/prettyprinter.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_PRETTYPRINTER_H_
 #define V8_PRETTYPRINTER_H_
 
 #include "src/allocation.h"
 #include "src/ast.h"
 
@@ skipping 115 matching lines @@
   void PrintProperties(ZoneList<ObjectLiteral::Property*>* properties);
 
   void inc_indent() { indent_++; }
   void dec_indent() { indent_--; }
 
   int indent_;
 };
 
 #endif  // DEBUG
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_PRETTYPRINTER_H_