Add annotation to report the use of concurrent root in TTRC

Summary:
Annotate use of `ConcurrentRoot` in React in performance logger.

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D34453147

fbshipit-source-id: 813a58ae964e5ae4ddf806a30597ee39d315e800

Libraries/ReactNative/renderApplication.js

@@ -64,6 +64,10 @@ function renderApplication<Props: Object>(
   }
 
   performanceLogger.startTimespan('renderApplication_React_render');
+  performanceLogger.setExtra(
+    'usedReactConcurrentRoot',
+    useConcurrentRoot ? '1' : '0',
+  );
   performanceLogger.setExtra('usedReactFabric', fabric ? '1' : '0');
   if (fabric) {
     require('../Renderer/shims/ReactFabric').render(