RFR: 8348423: [TestBug] stress test Nodes initialization from a background thread [v2]

[Andy Goryachev]

> Created a test that validates various Nodes can be initialized in a background thread.

Andy Goryachev has updated the pull request incrementally with one additional commit since the last revision:

  review comments

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1690/files
  - new: https://git.openjdk.org/jfx/pull/1690/files/8786bab5..d1356dce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1690&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1690&range=00-01

  Stats: 50 lines in 2 files changed: 16 ins; 11 del; 23 mod
  Patch: https://git.openjdk.org/jfx/pull/1690.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1690/head:pull/1690

PR: https://git.openjdk.org/jfx/pull/1690