[presubmit] Enable readability/namespace linter checking.

src/vm-state.h

 // Copyright 2010 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_VM_STATE_H_
 #define V8_VM_STATE_H_
 
 #include "src/allocation.h"
 #include "src/isolate.h"
 
@@ skipping 28 matching lines @@
 
  private:
   Isolate* isolate_;
   Address callback_;
   ExternalCallbackScope* previous_scope_;
 #ifdef USE_SIMULATOR
   Address scope_address_;
 #endif
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 
 #endif  // V8_VM_STATE_H_