RFR: 8370498: Improve how Node detects whether a layout property change requires a new layout pass [v3]

[John Hendrikx]

> This new check is much more accurate to detect whether a parent is currently laying out its children. The previous code almost never worked, resulting in additional unnecessary layouts.

John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:

  Add regression test

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1945/files
  - new: https://git.openjdk.org/jfx/pull/1945/files/a22ce090..79296325

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1945&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1945&range=01-02

  Stats: 141 lines in 1 file changed: 112 ins; 8 del; 21 mod
  Patch: https://git.openjdk.org/jfx/pull/1945.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1945/head:pull/1945

PR: https://git.openjdk.org/jfx/pull/1945