[presubmit] Enable readability/namespace linter checking.

src/variables.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.
 
 #ifndef V8_VARIABLES_H_
 #define V8_VARIABLES_H_
 
 #include "src/ast-value-factory.h"
 #include "src/zone.h"
 
@@ skipping 175 matching lines @@
   void set_declaration_group_start(int declaration_group_start) {
     declaration_group_start_ = declaration_group_start;
   }
 
  private:
   // For classes we keep track of consecutive groups of delcarations. They are
   // needed for strong mode scoping checks. TODO(marja, rossberg): Implement
   // checks for functions too.
   int declaration_group_start_;
 };
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_VARIABLES_H_