RFR: 8264677 MemoryLeak: Progressindicator leaks, when treeShowing is false [v4]

[Florian Kirmaier]

> Fixing leak in ProgressIndicator when treeShowing is false

Florian Kirmaier has updated the pull request incrementally with one additional commit since the last revision:

  8264677
  Readded countdownlatch for onShown based on code review

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/455/files
  - new: https://git.openjdk.java.net/jfx/pull/455/files/15fae375..ba02397a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=455&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=455&range=02-03

  Stats: 9 lines in 1 file changed: 9 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/455.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/455/head:pull/455

PR: https://git.openjdk.java.net/jfx/pull/455