[presubmit] Enable readability/namespace linter checking.

src/heap/incremental-marking-job.h

 // Copyright 2012 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_HEAP_INCREMENTAL_MARKING_JOB_H_
 #define V8_HEAP_INCREMENTAL_MARKING_JOB_H_
 
 #include "src/cancelable-task.h"
 
 namespace v8 {
@@ skipping 57 matching lines @@
   void NotifyDelayedTask();
   void NotifyIdleTaskProgress();
   void ScheduleIdleTask(Heap* heap);
   void ScheduleDelayedTask(Heap* heap);
 
  private:
   bool idle_task_pending_;
   bool delayed_task_pending_;
   bool made_progress_since_last_delayed_task_;
 };
-}
-}  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_HEAP_INCREMENTAL_MARKING_JOB_H_