[presubmit] Enable readability/namespace linter checking.

src/hydrogen-environment-liveness.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_HYDROGEN_ENVIRONMENT_LIVENESS_H_
 #define V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_
 
 
 #include "src/hydrogen.h"
 
@@ skipping 45 matching lines @@
   // Keeps track of the last simulate seen, as well as the environment slots
   // for which a new live range has started since (so they must not be zapped
   // in that simulate when the end of another live range of theirs is found).
   HSimulate* last_simulate_;
   BitVector went_live_since_last_simulate_;
 
   DISALLOW_COPY_AND_ASSIGN(HEnvironmentLivenessAnalysisPhase);
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif /* V8_HYDROGEN_ENVIRONMENT_LIVENESS_H_ */