RFR: 8314266: Several test failures after fix for JDK-8159048

[Jose Pereda]

This PR fixes some failing tests that started failing after the check on animations being played on the JavaFX thread was enforced, by simply wrapping the `play` call with `Platform.runLater`

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Commit messages:
 - Run timelines on JavaFX thread

Changes: https://git.openjdk.org/jfx/pull/1211/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1211&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314266
  Stats: 7 lines in 3 files changed: 1 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/1211.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1211/head:pull/1211

PR: https://git.openjdk.org/jfx/pull/1211