[presubmit] Enable readability/namespace linter checking.

include/v8.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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 128 matching lines @@
 class Arguments;
 class Heap;
 class HeapObject;
 class Isolate;
 class Object;
 struct StreamedSource;
 template<typename T> class CustomArguments;
 class PropertyCallbackArguments;
 class FunctionCallbackArguments;
 class GlobalHandles;
-}
+}  // namespace internal
 
 
 /**
  * General purpose unique identifier.
  */
 class UniqueId {
  public:
   explicit UniqueId(intptr_t data)
       : data_(data) {}
 
@@ skipping 8194 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_