RFR: 8370498: Improve how Node detects whether a layout property change requires a new layout pass [v5]

[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 with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge branch 'master' into feature/in-layoutchildren-detection-for-node
 - Rename test
 - Add regression test
 - 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.
 - Change how Node detects whether a relayout is required
   
   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.

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Changes: https://git.openjdk.org/jfx/pull/1945/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1945&range=04
  Stats: 180 lines in 3 files changed: 133 ins; 20 del; 27 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