RFR: JDK-8172095: Let Node.managed become CSS-styleable

[Abhinay Agarwal]

JDK-8172095: Let Node.managed become CSS-styleable

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Commit messages:
 - JDK-8172095: Let Node.managed become CSS-styleable

Changes: https://git.openjdk.java.net/jfx/pull/602/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=602&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8172095
  Stats: 39 lines in 4 files changed: 35 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jfx/pull/602.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/602/head:pull/602

PR: https://git.openjdk.java.net/jfx/pull/602