RFR: 8335633: Missing @Override in Dimension

[Andy Goryachev]

added missing @Override annotations

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Commit messages:
 - 8335633: Missing @Override in Dimension

Changes: https://git.openjdk.org/jfx/pull/1494/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1494&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335633
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/1494.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1494/head:pull/1494

PR: https://git.openjdk.org/jfx/pull/1494