[jdk11u-dev] RFR: 8320303: Allow PassFailJFrame to accept single window creator

[Andrew Lu]

I backport this for parity with 11.0.24-oracle.

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Commit messages:
 - Backport 83ffc1ac94b8893532d8663b9058592f1714d337

Changes: https://git.openjdk.org/jdk11u-dev/pull/2568/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2568&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320303
  Stats: 152 lines in 1 file changed: 125 ins; 6 del; 21 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2568.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2568/head:pull/2568

PR: https://git.openjdk.org/jdk11u-dev/pull/2568