Fix measure: missing early return

Summary:
In the refactor in D28933824 (https://github.com/facebook/react-native/commit/6b601db8b83337415113a123d780fb64aa67af42), an early return was accidentally deleted. This causes incorrect measurements to be returned, which can break a few things including Text Inline Views.

Changelog: [internal]

Reviewed By: mdvacca

Differential Revision: D29122235

fbshipit-source-id: 76c8991132e22cd4e0fc1c277447c4dba751adfb

ReactCommon/react/renderer/uimanager/UIManagerBinding.cpp

@@ -703,6 +703,7 @@ jsi::Value UIManagerBinding::get(
 
                 if (layoutMetrics == EmptyLayoutMetrics) {
                   onSuccess->call(runtime, {0, 0, 0, 0, 0, 0});
+                  return;
                 }
                 auto newestCloneOfShadowNode =
                     uiManager->getNewestCloneOfShadowNode(*shadowNode);