[presubmit] Enable readability/namespace linter checking.

src/ppc/code-stubs-ppc.h

 // Copyright 2014 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_PPC_CODE_STUBS_PPC_H_
 #define V8_PPC_CODE_STUBS_PPC_H_
 
 #include "src/ppc/frames-ppc.h"
 
 namespace v8 {
@@ skipping 304 matching lines @@
       NameDictionary::kHeaderSize +
       NameDictionary::kElementsStartIndex * kPointerSize;
 
   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_PPC_CODE_STUBS_PPC_H_