RFR: 8196065: ListChangeListener getRemoved() returns items that were not removed. [v9]

[Michael Strauß]

> The documentation for `ObservableListBase.nextRemove` states that a single change always refers to the current state of the list, which likely means that multiple disjoint removed ranges need to be applied in order, otherwise the next change's `getFrom` doesn't refer to the correct index.
> 
> `SelectedItemsReadOnlyObservableList` doesn't apply removals to `itemsRefList`, which means that subsequent removals will refer to the wrong index when retrieving the removed elements. This PR fixes the calculation of the current index.

Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:

  changes as per review comments

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

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/478/files
  - new: https://git.openjdk.java.net/jfx/pull/478/files/20fdb393..1672f4da

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=478&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=478&range=07-08

  Stats: 53 lines in 3 files changed: 0 ins; 34 del; 19 mod
  Patch: https://git.openjdk.java.net/jfx/pull/478.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/478/head:pull/478

PR: https://git.openjdk.java.net/jfx/pull/478