RFR: 8377193: Remove AppContext from SwingUtilties3

[Phil Race]

Remove AppContext from SU3

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Commit messages:
 - 8377193

Changes: https://git.openjdk.org/jdk/pull/29580/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29580&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377193
  Stats: 9 lines in 1 file changed: 2 ins; 3 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/29580.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29580/head:pull/29580

PR: https://git.openjdk.org/jdk/pull/29580