Expressions that return two slots primitives are broken

[Paullo612]

Steps to reproduce:

1. Clone mlfx-samle project.
2. Replace contents of src/main/resources/hellofxml/hello.fxml with following FXML code:

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.VBox?>


<AnchorPane fx:id="pane" prefHeight="400.0" prefWidth="600.0" stylesheets="@style.css" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="hellofx.HelloController">
   <children>
      <VBox layoutX="223.0" layoutY="166.0" prefHeight="400.0" prefWidth="600.0" styleClass="box" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
         <children>
            <Button prefWidth="${pane.width}" fx:id="button" mnemonicParsing="false" text="%button.text" />
            <Label fx:id="label" text="%label.text" visible="false" />
         </children>
      </VBox>
   </children>
</AnchorPane>

3. Observe java.lang.VerifyError:

Caused by: java.lang.VerifyError: Bad type on operand stack
Exception Details:
  Location:
    hellofxml/$Hello$CompiledFXMLLoader$Expression0.update(I)V @100: swap
  Reason:
    Type double_2nd (current frame, stack[1]) is not assignable to category1 type
  Current Frame:
    bci: @100
    flags: { }
    locals: { 'hellofxml/$Hello$CompiledFXMLLoader$Expression0', integer, integer }
    stack: { double, double_2nd, 'hellofxml/$Hello$CompiledFXMLLoader$Expression0' }
  Bytecode:
    0000000: 2ab4 0016 b900 1c01 0003 3d1b aa00 0000
    0000010: 0000 0049 0000 0000 0000 0001 0000 0018
    0000020: 0000 0046 2ab4 0016 2ab4 0022 03b9 0026
    0000030: 0300 2a2a b400 22b6 002c b500 2e2a b400
    0000040: 162a b400 222a b400 22b6 0032 03b9 0036
    0000050: 0400 a700 0dbb 0038 5912 3ab7 003e bf2a
    0000060: b400 2e2a 5fb6 0044 2ab4 0016 b900 4701
    0000070: 00a7 000f 4d2a b400 16b9 0047 0100 2cbf
    0000080: b1                                     
  Exception Handler Table:
    bci [9, 104] => handler: 116
  Stackmap Table:
    append_frame(@36,Integer)
    same_frame(@82)
    same_frame(@85)
    same_frame(@95)
    full_frame(@116,{Object[#2],Integer},{Object[#73]})
    append_frame(@128,Integer)
	at hellofxml/hellofxml.$Hello$CompiledFXMLLoader.doLoad(Unknown Source)
	at hellofxml/hellofxml.$Hello$CompiledFXMLLoader.doLoad(Unknown Source)
	at io.github.paullo612.mlfx.api.core@0.6.1-SNAPSHOT/io.github.paullo612.mlfx.api.CompiledFXMLLoader.load(CompiledFXMLLoader.java:133)
	at io.github.paullo612.mlfx.api.core@0.6.1-SNAPSHOT/io.github.paullo612.mlfx.api.MLFXLoader.load(MLFXLoader.java:310)
	at io.github.paullo612.mlfx.api.core@0.6.1-SNAPSHOT/io.github.paullo612.mlfx.api.MLFXLoader.load(MLFXLoader.java:63)
	at hellofxml/hellofx.HelloFXML.start(HelloFXML.java:50)
	at javafx.graphics@20/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:839)
	at javafx.graphics@20/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:483)
	at javafx.graphics@20/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at javafx.graphics@20/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
	at javafx.graphics@20/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
	at javafx.graphics@20/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
	at javafx.graphics@20/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$11(GtkApplication.java:316)
	... 1 more