import javafx.application.Application;
import javafx.scene.web.WebEngine;
import javafx.stage.Stage;

/**
 *
 * @author andrey.rusakov@oracle.com
 */
public class WebkitJSCrash extends Application {

    private WebEngine engine;
    private Object resultObject;

    public static void main(String[] args) {
        Application.launch(args);
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        engine = new WebEngine();
        resultObject = engine.executeScript("document.createElement('span')");
        new Thread(() -> {
            System.out.println(resultObject);
        }).start();
    }
}