RFR: 8256821: TreeViewSkin/Behavior: misbehavior on switching skin [v2]

[Jeanette Winzenburg]

> issues with behavior:
> - memory leak due to an key eventHandler that's not removed
> - after dispose, still modifying treeView (anchor) state due to listeners selection that are not removed
> 
> issues with skin:
> - memory leak due to behavior leaking
> - memory leak due to cellFactory in flow not removed
> - throws NPE after switching (on modifying root children, refresh) due to listeners not removed
> 
> Fixed by cleaning up as needed. Added tests that are failing before and passing after the fix.

Jeanette Winzenburg has updated the pull request incrementally with one additional commit since the last revision:

  fixed c&p naming error

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/358/files
  - new: https://git.openjdk.java.net/jfx/pull/358/files/1275c5fb..007c6f77

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=358&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=358&range=00-01

  Stats: 16 lines in 1 file changed: 0 ins; 0 del; 16 mod
  Patch: https://git.openjdk.java.net/jfx/pull/358.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/358/head:pull/358

PR: https://git.openjdk.java.net/jfx/pull/358