RFR: 8185937 - Spinner with Double/Integer value factory ignores up/down arrow keys

[Scott Palmer]

Please review the fix for 	JDK-8185937 - Spinner with Double/Integer value factory ignores up/down arrow keys

https://bugs.openjdk.java.net/browse/JDK-8185937 <https://bugs.openjdk.java.net/browse/JDK-8185937>
 
https://github.com/javafxports/openjdk-jfx/pull/517 <https://github.com/javafxports/openjdk-jfx/pull/517>