[presubmit] Enable readability/namespace linter checking.

src/arm64/code-stubs-arm64.h

 // Copyright 2013 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_ARM64_CODE_STUBS_ARM64_H_
 #define V8_ARM64_CODE_STUBS_ARM64_H_
 
 namespace v8 {
 namespace internal {
 
@@ skipping 366 matching lines @@
       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_ARM64_CODE_STUBS_ARM64_H_