[jdk11u-dev] RFR: 8306640: Open source several AWT TextArea related tests

[Andrew Lu]

I backport this for parity with 11.0.24-oracle.

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Commit messages:
 - Backport 169a7c27a7c6521fbfb1e61fbe85e6d7b0470619

Changes: https://git.openjdk.org/jdk11u-dev/pull/2527/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2527&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/jdk11u-dev/pull/2527.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2527/head:pull/2527

PR: https://git.openjdk.org/jdk11u-dev/pull/2527