[presubmit] Enable readability/namespace linter checking.

src/context-measure.h

 // 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.
 
 #ifndef V8_CONTEXT_MEASURE_H_
 #define V8_CONTEXT_MEASURE_H_
 
 #include "src/snapshot/serialize.h"
 
 namespace v8 {
@@ skipping 23 matching lines @@
   int recursion_depth_;
   List<HeapObject*> deferred_objects_;
 
   int count_;
   int size_;
 
   DisallowHeapAllocation no_gc_;
 
   DISALLOW_COPY_AND_ASSIGN(ContextMeasure);
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_CONTEXT_MEASURE_H_