[jdk17u-dev] RFR: 8306640: Open source several AWT TextArea related tests

[Victor Rudometov]

Clean backport, new tests, low risk
Checked on macOS x64, linux x64, windows x64: tests pass

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Commit messages:
 - Backport 169a7c27a7c6521fbfb1e61fbe85e6d7b0470619

Changes: https://git.openjdk.org/jdk17u-dev/pull/1368/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1368&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306640
  Stats: 437 lines in 4 files changed: 437 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1368.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1368/head:pull/1368

PR: https://git.openjdk.org/jdk17u-dev/pull/1368