[presubmit] Enable readability/namespace linter checking.

src/ppc/assembler-ppc.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 1594 matching lines @@
   PositionsRecorder positions_recorder_;
   friend class PositionsRecorder;
   friend class EnsureSpace;
 };
 
 
 class EnsureSpace BASE_EMBEDDED {
  public:
   explicit EnsureSpace(Assembler* assembler) { assembler->CheckBuffer(); }
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_PPC_ASSEMBLER_PPC_H_