RFR: 8370498: Improve how Node detects whether a layout property change requires a new layout pass [v2]

[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:

  Fix ToolBarSkinTest
  
  Reusing a toolbar as part of several scenes, in combination with the StubToolkit that doesn't handle pulses makes this test fail with the relayout detection fix.

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1945/files
  - new: https://git.openjdk.org/jfx/pull/1945/files/19246b63..a22ce090

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1945&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1945&range=00-01

  Stats: 12 lines in 1 file changed: 6 ins; 6 del; 0 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