RFR: 8378377: Remove use of AppContext from JEditorPane

[Phil Race]

Remove AppContext from JEditorPane

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Commit messages:
 - 8378377

Changes: https://git.openjdk.org/jdk/pull/29855/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29855&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378377
  Stats: 73 lines in 1 file changed: 16 ins; 52 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/29855.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29855/head:pull/29855

PR: https://git.openjdk.org/jdk/pull/29855