RFR: 8315669: Open source several Swing PopupMenu related tests

[Tejesh R]

Open source these Swing PopupMenu related tests:

javax/swing/JPopupMenu/4236750/bug4236750.java
javax/swing/JPopupMenu/4321273/bug4321273.java
javax/swing/JPopupMenu/4711693/bug4711693.java
javax/swing/JPopupMenu/4962731/bug4962731.java
javax/swing/JPopupMenu/4966109/bug4966109.java
javax/swing/JPopupMenu/5091257/bug5091257.java

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Commit messages:
 - Open sourcing few Popupmenu test

Changes: https://git.openjdk.org/jdk/pull/15704/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15704&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315669
  Stats: 754 lines in 6 files changed: 754 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15704.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15704/head:pull/15704

PR: https://git.openjdk.org/jdk/pull/15704