[presubmit] Enable readability/namespace linter checking.

test/cctest/print-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 24 matching lines @@
 
 class PrintExtension : public v8::Extension {
  public:
   PrintExtension() : v8::Extension("v8/print", "native function print();") { }
   virtual v8::Handle<v8::FunctionTemplate> GetNativeFunctionTemplate(
       v8::Isolate* isolate,
       v8::Handle<v8::String> name);
   static void Print(const v8::FunctionCallbackInfo<v8::Value>& args);
 };
 
-} }  // namespace v8::internal
+}  // namespace internal
+}  // namespace v8
 
 #endif