[presubmit] Enable readability/namespace linter checking.

src/hydrogen-flow-engine.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_FLOW_ENGINE_H_
 #define V8_HYDROGEN_FLOW_ENGINE_H_
 
 #include "src/hydrogen.h"
 #include "src/hydrogen-instructions.h"
 #include "src/zone.h"
@@ skipping 196 matching lines @@
   HGraph* graph_;                    // The hydrogen graph.
   Zone* zone_;                       // Temporary zone.
 #if DEBUG
   ZoneList<int> pred_counts_;        // Finished predecessors (by block id).
 #endif
   ZoneList<State*> block_states_;    // Block states (by block id).
   ZoneList<Effects*> loop_effects_;  // Loop effects (by block id).
 };
 
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_HYDROGEN_FLOW_ENGINE_H_