[presubmit] Enable readability/namespace linter checking.

src/mips64/code-stubs-mips64.h

 // Copyright 2011 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_MIPS_CODE_STUBS_MIPS64_H_
 #define V8_MIPS_CODE_STUBS_MIPS64_H_
 
 #include "src/mips64/frames-mips64.h"
 
 namespace v8 {
@@ skipping 326 matching lines @@
 
   LookupMode mode() const { return LookupModeBits::decode(minor_key_); }
 
   class LookupModeBits: public BitField<LookupMode, 0, 1> {};
 
   DEFINE_NULL_CALL_INTERFACE_DESCRIPTOR();
   DEFINE_PLATFORM_CODE_STUB(NameDictionaryLookup, PlatformCodeStub);
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_MIPS_CODE_STUBS_MIPS64_H_