RFR: 8267094: TreeCell: cancelEvent must return correct editing location [v2]

[Jeanette Winzenburg]

> the bug is an incorrect edit location (for tree: treeItem) in edit cancel events - expected is the location at the time the cell edit was started, actual was the location of at the time the edit was cancelled. See the report for details.
> 
> Fixed by storing the edit location in startEdit and use that in cancelEdit.
> 
> Added tests that failed before and passed after and tests that (accidentally :) passed before and still pass after.

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

  fixed memory leak introduced in previous version

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/524/files
  - new: https://git.openjdk.java.net/jfx/pull/524/files/ab2da1e4..ea3b705f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=524&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=524&range=00-01

  Stats: 74 lines in 2 files changed: 74 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/524.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/524/head:pull/524

PR: https://git.openjdk.java.net/jfx/pull/524