Wrong rendering of variation sequences

ADDITIONAL SYSTEM INFORMATION :
All OS (Windows, Linux, etc.)

A DESCRIPTION OF THE PROBLEM :
JavaFX does not display variation selectors.

This bug is related with SWING bug.
https://bugs.openjdk.java.net/browse/JDK-8187100
SWING was fixed from openjdk11.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Please run following VariationSelectorsTest.java

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
https://drive.google.com/open?id=1CU9r_pm0t5EO8dHj1yLgnKPB2J4ECDsp
ACTUAL -
https://drive.google.com/open?id=1lJKavmqlj0XDckR6UR_xIT1Eiag7CZHl

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import static javafx.application.Application.launch;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class VariationSelectorsTest extends Application {

    public void start(Stage stage) {
        final String fontName = "ipaexm.ttf";
        // download from https://ipafont.ipa.go.jp/node26#en
        // and place in {user.home}/fonts/

        final String base = System.getProperty("user.home")+"/fonts/";
        Font font = Font.loadFont("file://"+base+fontName, 48);
        if (font == null || !"IPAexMincho".equals(font.getName())) {
            System.err.println("# You need to place "+fontName+" in "+base);
            System.exit(0);
        }

        stage.setWidth(260);
        stage.setHeight(80);
        Group g = new Group();
        final Scene scene = new Scene(new Group());
        VBox box = new VBox();
        ((Group)scene.getRoot()).getChildren().add(box);
        stage.setScene(scene);

        Text txt = new Text("\u845b\udb40\udd00\u845b\udb40\udd01");
        txt.setFont(font);
        box.getChildren().add(txt);

        stage.show();
    }
}
---------- END SOURCE ----------

FREQUENCY : always