[presubmit] Enable readability/namespace linter checking.

src/small-pointer-list.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_SMALL_POINTER_LIST_H_
 #define V8_SMALL_POINTER_LIST_H_
 
 #include "src/base/logging.h"
 #include "src/globals.h"
 #include "src/zone.h"
@@ skipping 152 matching lines @@
   PointerList* list() const {
     DCHECK((data_ & kTagMask) == kListTag);
     return reinterpret_cast<PointerList*>(data_ & kValueMask);
   }
 
   intptr_t data_;
 
   DISALLOW_COPY_AND_ASSIGN(SmallPointerList);
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_SMALL_POINTER_LIST_H_