[jdk11u-dev] RFR: 8289547: Update javax/swing/Popup/TaskbarPositionTest.java

[Amos]

- Backport of [JDK-8289547](https://bugs.openjdk.org/browse/JDK-8289547)
- Verified work in local

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Commit messages:
 - Backport d73fc70ea272be6bf4f1c82608c73ff0a8f6032d

Changes: https://git.openjdk.org/jdk11u-dev/pull/2165/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2165&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289547
  Stats: 246 lines in 1 file changed: 132 ins; 54 del; 60 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2165.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2165/head:pull/2165

PR: https://git.openjdk.org/jdk11u-dev/pull/2165