[presubmit] Enable readability/namespace linter checking.

src/effects.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_EFFECTS_H_
 #define V8_EFFECTS_H_
 
 #include "src/types.h"
 
 namespace v8 {
@@ skipping 311 matching lines @@
   }
 
   NestedEffects Pop() {
     NestedEffects result = *this;
     result.pop();
     DCHECK(!this->is_empty());
     return result;
   }
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_EFFECTS_H_