RFR: 8315611: Open source swing text/html and tree test

[Prasanta Sadhukhan]

Few closed swing text/html and tree tests are opensourced

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Commit messages:
 - 8315611: Open source swing text/html and tree test

Changes: https://git.openjdk.org/jdk/pull/15608/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15608&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315611
  Stats: 469 lines in 4 files changed: 469 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15608.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15608/head:pull/15608

PR: https://git.openjdk.org/jdk/pull/15608