[jfx25] RFR: 8364088: ToolBarSkin: NPE in select()

[Andy Goryachev]

Fixed an NPE in the ToolBar.

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Commit messages:
 - Backport 450ca6da16c5299d9792d01009a4400daa87ce6a

Changes: https://git.openjdk.org/jfx/pull/1861/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1861&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364088
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1861.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1861/head:pull/1861

PR: https://git.openjdk.org/jfx/pull/1861