RFR: 8290765: Remove parent disabled/treeVisible listeners [v2]

[Michael Strauß]

> `Node` adds InvalidationListeners to its parent's `disabled` and `treeVisible` properties and calls its own `updateDisabled()` and `updateTreeVisible(boolean)` methods when the property values change.
> 
> These listeners are not required, since `Node` can easily call the `updateDisabled()` and `updateTreeVisible(boolean)` methods on its children, saving the memory cost of maintaining listeners and bindings.

Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Replace null check by explicit underConstruction flag
 - Merge branch 'master' into fixes/node-listener-cleanup
 - Merge
 - added tests
 - Remove Node.disabled and Node.treeVisible listeners

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Changes: https://git.openjdk.org/jfx/pull/841/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=841&range=01
  Stats: 81 lines in 4 files changed: 53 ins; 10 del; 18 mod
  Patch: https://git.openjdk.org/jfx/pull/841.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/841/head:pull/841

PR: https://git.openjdk.org/jfx/pull/841