RFR: 8187474: Tree-/TableCell, TreeCell: editingCell/Item not updated in cell.startEdit [v2]

[Jeanette Winzenburg]

> cell startEdit is supposed to update the editing location on its associated control - was done in ListCell, not in Tree-/TableCell nor TreeCell.
> 
> Fix was to add control.edit(..). Note that ListCell was also touched to use the exact same method call pattern as the fixed cell types.
> 
> Added/unignored cell tests that are failing/passing before/after the fix.

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

  fixed formatting as suggested in review
  
  and removed unused (by this fix) import in same file

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

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/638/files
  - new: https://git.openjdk.java.net/jfx/pull/638/files/050a6caa..4f76e1fe

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=638&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=638&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/638.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/638/head:pull/638

PR: https://git.openjdk.java.net/jfx/pull/638