[presubmit] Enable readability/namespace linter checking.

src/heap/array-buffer-tracker.h

 // Copyright 2015 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_HEAP_ARRAY_BUFFER_TRACKER_H_
 #define V8_HEAP_ARRAY_BUFFER_TRACKER_H_
 
 #include <map>
 
 #include "src/globals.h"
@@ skipping 50 matching lines @@
 
   // To be able to free memory held by ArrayBuffers during scavenge as well, we
   // have a separate list of allocated memory held by ArrayBuffers in new space.
   //
   // Since mark/compact also evacuates the new space, all pointers in the
   // |live_array_buffers_for_scavenge_| list are also in the
   // |live_array_buffers_| list.
   std::map<void*, size_t> live_array_buffers_for_scavenge_;
   std::map<void*, size_t> not_yet_discovered_array_buffers_for_scavenge_;
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 #endif  // V8_HEAP_ARRAY_BUFFER_TRACKER_H_