<Swing Dev> RFR: 8171998: javax/swing/JMenu/4692443/bug4692443.java fails on Windows

[Prasanta Sadhukhan]

Please review a test fix for an issue seen to be failing in mach5 testing. Although initially the failure was reported on windows, it is problemlisted only for mac.
It seems to be a timing issue resulting in failure in mach5 macos systems so added a delay after the frame setVisible is called. Also, moved the frame to centre of screen to be consistent with other tests.
Mach5 job has been run for several iterations in all platforms. Link in JBS.

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Commit messages:
 - 8171998: javax/swing/JMenu/4692443/bug4692443.java fails on Windows

Changes: https://git.openjdk.java.net/jdk/pull/873/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=873&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8171998
  Stats: 6 lines in 2 files changed: 3 ins; 2 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/873.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/873/head:pull/873

PR: https://git.openjdk.java.net/jdk/pull/873