RFR: 8256649: Parameterized tests must not use instances as parameters

[Jeanette Winzenburg]

the issue was an (my ;) overzealous refactoring when introducing support for cross-control testing for memory leaks on switching skins.

Fixed by
- using control class as parameter
- instantiate the control at setup time

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Commit messages:
 - 8256649: Parameterized tests must not use instances as parameters

Changes: https://git.openjdk.java.net/jfx/pull/356/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=356&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256649
  Stats: 23 lines in 2 files changed: 4 ins; 13 del; 6 mod
  Patch: https://git.openjdk.java.net/jfx/pull/356.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/356/head:pull/356

PR: https://git.openjdk.java.net/jfx/pull/356