[presubmit] Enable readability/namespace linter checking.

test/cctest/trace-extension.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 34 matching lines @@
   static void JSEntrySP(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void JSEntrySPLevel2(const v8::FunctionCallbackInfo<v8::Value>& args);
   static Address GetJsEntrySp();
   static void InitTraceEnv(TickSample* sample);
   static void DoTrace(Address fp);
  private:
   static Address GetFP(const v8::FunctionCallbackInfo<v8::Value>& args);
   static const char* kSource;
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif