RFR: 8295339: DatePicker updates its value property with wrong date when dialog closes [v2]

[Karthik P K]

> Cause: On hiding the DatePicker dropdown, value selected was not getting updated to the text editor. Hence old value from the text editor was getting committed to DatePicker on focus loss. This issue was seen only when DatePicker is used in Alert dialog and Alert dialog is closed on making selection in DatePicker dropdown.
> 
> Fix: Added call to updateDisplayNode() function before hiding the date picker dropdown.
> 
> Test: Added system test to validate the fix.

Karthik P K has updated the pull request incrementally with one additional commit since the last revision:

  Address review comments

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Changes:
  - all: https://git.openjdk.org/jfx/pull/963/files
  - new: https://git.openjdk.org/jfx/pull/963/files/7b9448f8..7f7eb42b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=963&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=963&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/963.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/963/head:pull/963

PR: https://git.openjdk.org/jfx/pull/963