RFR: 8284014 Menu items with submenus in JPopupMEnu are not spoken on macOS

[Artem Semenov]

If the JPopupMenu has menu items with submenus, those items are not spoken by VoiceOver.

@forantar @azuev-java please review.

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Commit messages:
 - 8284014 Menu items with submenus in JPopupMEnu are not spoken on macOS

Changes: https://git.openjdk.java.net/jdk/pull/8043/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8043&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284014
  Stats: 111 lines in 3 files changed: 106 ins; 2 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8043.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8043/head:pull/8043

PR: https://git.openjdk.java.net/jdk/pull/8043