UIManager.findNodeAtPoint now returns shadowNode instead of instanceHandle

Summary:
Changelog: [Internal]

As agreed in https://fb.quip.com/Oh2mAaTAbBj6, `findNodeAtPoint` now calls callback with `shadowNode` instead of `instanceHandle`.

Reviewed By: shergin

Differential Revision: D20097269

fbshipit-source-id: bd2a1bcd26ab2510f16c3e73f628be4b1f7dacfc

ReactCommon/fabric/core/events/EventEmitter.h

@@ -81,8 +81,6 @@ class EventEmitter {
  private:
   void toggleEventTargetOwnership_() const;
 
-  friend class UIManagerBinding;
-
   mutable SharedEventTarget eventTarget_;
 
   EventDispatcher::Weak eventDispatcher_;

ReactCommon/fabric/uimanager/UIManagerBinding.cpp

@@ -268,15 +268,8 @@ jsi::Value UIManagerBinding::get(
               arguments[3].getObject(runtime).getFunction(runtime);
           auto targetNode =
               uiManager->findNodeAtPoint(node, Point{locationX, locationY});
-          auto &eventTarget = targetNode->getEventEmitter()->eventTarget_;
   
-          EventEmitter::DispatchMutex().lock();
-          eventTarget->retain(runtime);
-          auto instanceHandle = eventTarget->getInstanceHandle(runtime);
-          eventTarget->release(runtime);
-          EventEmitter::DispatchMutex().unlock();
-
-          onSuccessFunction.call(runtime, std::move(instanceHandle));
+          onSuccessFunction.call(runtime, valueFromShadowNode(runtime, targetNode));
           return jsi::Value::undefined();
         });
   }