[presubmit] Enable readability/namespace linter checking.

src/x64/simulator-x64.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_X64_SIMULATOR_X64_H_
 #define V8_X64_SIMULATOR_X64_H_
 
 #include "src/allocation.h"
 
 namespace v8 {
@@ skipping 23 matching lines @@
     return c_limit;
   }
 
   static inline uintptr_t RegisterCTryCatch(uintptr_t try_catch_address) {
     return try_catch_address;
   }
 
   static inline void UnregisterCTryCatch() { }
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_X64_SIMULATOR_X64_H_