iOS: implement <PerformanceLoggerFlag> component

Summary: This is basic impl of <PerformanceLoggerFlag> component without any layout/mounting computation, just TTI.

Reviewed By: shergin, mdvacca

Differential Revision: D8598983

fbshipit-source-id: b938753d6396088735cbbeab26d69c9aaa45608e

ReactCommon/fabric/uimanager/FabricUIManager.cpp

@@ -65,10 +65,8 @@ static const std::string componentNameByReactViewName(std::string viewName) {
   }
 
   // We need this temporarly for testing purposes until we have proper
-  // implementation of core components: <ReactPerformanceLoggerFlag>,
-  // <SafeAreaView>, and etc.
+  // implementation of core components.
   if (
-    viewName == "ReactPerformanceLoggerFlag" ||
     viewName == "SinglelineTextInputView" ||
     viewName == "MultilineTextInputView" ||
     viewName == "RefreshControl" ||