RFR: 8245145: Spinner: throws IllegalArgumentException when replacing skin

[Andy Goryachev]

Fixed SpinnerSkin initialization using new Skin.install().  Also in this PR - fixing memory leaks in SpinnerSkin by properly removing all listeners and event filters added in the constructor, as well as any child Nodes.

NOTE: the fix requires both ListenerHelper [JDK-8294809](https://bugs.openjdk.org/browse/JDK-8294809) and Skin.install() [JDK-8290844](https://bugs.openjdk.org/browse/JDK-8290844) changes.

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Commit messages:
 - 8245145: cleanup
 - 8245145: cleanup
 - 8245145: cleanup
 - Merge remote-tracking branch 'origin/master' into 8245145.spinner.skin
 - 8245145: listener helper
 - Merge branch '8294809.listener.helper' into 8245145.spinner.skin
 - 8294809: whitespace
 - 8294809: no public api
 - 8294809: map change listener
 - Merge remote-tracking branch 'origin/master' into 8294809.listener.helper
 - ... and 39 more: https://git.openjdk.org/jfx/compare/3376228a...bcb9c5f2

Changes: https://git.openjdk.org/jfx/pull/904/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=904&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8245145
  Stats: 61 lines in 3 files changed: 33 ins; 15 del; 13 mod
  Patch: https://git.openjdk.org/jfx/pull/904.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/904/head:pull/904

PR: https://git.openjdk.org/jfx/pull/904