Fabric: Exposing `findShadowNodeByTag_DEPRECATED` to JavaScript

Summary: This allows to implement `findNodeHandle` in Fabric world (temporary).

Reviewed By: zackargyle, JoshuaGross, mdvacca

Differential Revision: D17175953

fbshipit-source-id: c88bd1c58608450812799d4ecb4a6bf2c027c5f3

Libraries/ReactNative/FabricUIManager.js

@@ -48,6 +48,7 @@ type Spec = {|
     onFail: () => void,
     onSuccess: MeasureLayoutOnSuccessCallback,
   ) => void,
+  +findShadowNodeByTag_DEPRECATED: (reactTag: number) => ?Node,
 |};
 
 const FabricUIManager: ?Spec = global.nativeFabricUIManager;

ReactCommon/fabric/uimanager/UIManagerBinding.cpp

@@ -525,6 +525,27 @@ jsi::Value UIManagerBinding::get(
         });
   }
 
+  if (methodName == "findShadowNodeByTag_DEPRECATED") {
+    return jsi::Function::createFromHostFunction(
+        runtime,
+        name,
+        1,
+        [uiManager](
+            jsi::Runtime &runtime,
+            jsi::Value const &thisValue,
+            jsi::Value const *arguments,
+            size_t count) -> jsi::Value {
+          auto shadowNode = uiManager->findShadowNodeByTag_DEPRECATED(
+              tagFromValue(runtime, arguments[0]));
+
+          if (!shadowNode) {
+            return jsi::Value::null();
+          }
+
+          return valueFromShadowNode(runtime, shadowNode);
+        });
+  }
+
   return jsi::Value::undefined();
 }