[presubmit] Enable readability/namespace linter checking.

src/runtime/runtime-atomics.cc

 // 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.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/base/macros.h"
 #include "src/base/platform/mutex.h"
 #include "src/conversions-inl.h"
@@ skipping 703 matching lines @@
 }
 
 
 RUNTIME_FUNCTION(Runtime_AtomicsIsLockFree) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_NUMBER_ARG_HANDLE_CHECKED(size, 0);
   uint32_t usize = NumberToUint32(*size);
   return isolate->heap()->ToBoolean(AtomicIsLockFree(usize));
 }
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8