RFR: 8275071: [macos] A11y cursor gets stuck when combobox is closed

[Alexander Zuev]

Before the new JList accessibility peer implementation sending popup closed
event to the combobox popup could trigger the native memory access error due
to the events arriving in the wrong order. After new implementation is done
it is no longer the case and this workaround needs to be removed.

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Commit messages:
 - 8275071: [macos] A11y cursor gets stuck when combobox is closed

Changes: https://git.openjdk.java.net/jdk/pull/6422/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6422&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275071
  Stats: 18 lines in 1 file changed: 0 ins; 6 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6422.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6422/head:pull/6422

PR: https://git.openjdk.java.net/jdk/pull/6422