RFR: 8251483: TableCell: NPE on modifying item's list [v2]

[Marius Hanl]

> This PR fixes an issue where the item of the table row is null, although the cell itself is not empty (non null value).
> 
> The fix is to call `indexChanged(..)` immediately after the index was changed, but before all `indexProperty()` listener are notified.
> The then notified listener in `TableRowSkinBase` will update the underlying cells, which will eventually result in an call to  `updateItem(..)`, where the NPE happened (and now not anymore, since the table row is now correctly setup before).
> 
> There is one special case: When the index didn't changed at all, we manually call `indexChanged(..)` (basically just like before) since when a property is not changed, `invalidated()` is not called, but we need to notify subclasses that `updateIndex(..)` was called.

Marius Hanl has updated the pull request incrementally with one additional commit since the last revision:

  8251483: Updated copyright year

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/741/files
  - new: https://git.openjdk.java.net/jfx/pull/741/files/5f65b82c..23921bf2

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=741&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=741&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/741.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/741/head:pull/741

PR: https://git.openjdk.java.net/jfx/pull/741