[presubmit] Enable readability/namespace linter checking.

src/futex-emulation.h

 // Copyright 2015 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_FUTEX_EMULATION_H_
 #define V8_FUTEX_EMULATION_H_
 
 #include <stdint.h>
 
 #include "src/allocation.h"
@@ skipping 107 matching lines @@
   static Object* NumWaitersForTesting(Isolate* isolate,
                                       Handle<JSArrayBuffer> array_buffer,
                                       size_t addr);
 
  private:
   friend class FutexWaitListNode;
 
   static base::LazyMutex mutex_;
   static base::LazyInstance<FutexWaitList>::type wait_list_;
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_FUTEX_EMULATION_H_