[presubmit] Enable readability/namespace linter checking.

src/regexp/regexp-macro-assembler-irregexp.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_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_
 #define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_
 
 #include "src/regexp/regexp-macro-assembler.h"
 
 namespace v8 {
@@ skipping 107 matching lines @@
 
   Isolate* isolate_;
 
   static const int kInvalidPC = -1;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(RegExpMacroAssemblerIrregexp);
 };
 
 #endif  // V8_INTERPRETED_REGEXP
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_IRREGEXP_H_