Various extension-related cleanup and simplifications.

src/extensions/statistics-extension.h

Index: src/extensions/statistics-extension.h
diff --git a/src/extensions/statistics-extension.h b/src/extensions/statistics-extension.h
index f05e7689e737ed92fc59a5bfa90e2bc85c5a74ac..9e97b45dd6389c0cf5d06c5bf765a182c5beba44 100644
--- a/src/extensions/statistics-extension.h
+++ b/src/extensions/statistics-extension.h
@@ -40,7 +40,7 @@ class StatisticsExtension : public v8::Extension {
       v8::Isolate* isolate,
       v8::Handle<v8::String> name);
   static void GetCounters(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void Register();
+
  private:
   static const char* const kSource;
 };