[Rev 01] RFR: 8237926: Potential memory leak of model data in javafx.scene.control.ListView

[Ambarish Rapte]

> The selection model of ListView stores a strong reference to the most recently changed item in `SelectedItemsReadOnlyObservableList.itemsListChange`, which causes a leak.
> 
> Fix: 
> The below member variables and method of class SelectedItemsReadOnlyObservableList are not required anymore.
> Variables: itemsList, itemsListChanged, itemsListChange, itemsListListener.
> Method: setItemsList
> 
> These members were added when this class was created for [JDK-8154216](https://bugs.openjdk.java.net/browse/JDK-8154216).
> But after the fix for [JDK-8152396](https://bugs.openjdk.java.net/browse/JDK-8152396), these class members are not required.
> 
> Verification:
> No failure in existing tests and added a new test.

The pull request has been updated with 1 additional commit.

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

Added commits:
 - 42b454e0: adding test

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/132/files
  - new: https://git.openjdk.java.net/jfx/pull/132/files/c859a929..42b454e0

Webrevs:
 - full: https://webrevs.openjdk.java.net/jfx/132/webrev.01
 - incr: https://webrevs.openjdk.java.net/jfx/132/webrev.00-01

  Stats: 12 lines in 1 file changed: 10 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jfx/pull/132.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/132/head:pull/132

PR: https://git.openjdk.java.net/jfx/pull/132