[macosx] Incorrect VoiceOver cursor behavior when selecting JList items

- make sure VoiceOver is set up as follows:
  - System Preferences, Accessibility, VoiceOver, Open VoiceOver Utility, Navigation
  - In Grouping behavior: Ignore groups
  - Keyboard focus follows VoiceOver cursor: checked
  - VoiceOver cursor follow keyboard focus: checked
- start VoiceOver
- start SwingSet2
- click the ListDemo toolbar button to select the ListDemo
- press control + option + right arrow 10 times to move focus to the text above the list box
- press control + option + down arrow 1 time to move focus to the list
- press shift + control + down arrow to interact with the list

When using control + option + down arrow selection should move down one list item but the selection is getting extended instead.

This worked back when JDK-8145207 was pushed. Now it no longer works. I put the current 9 repo back to the point where the patch was pushed and the bug still occurs so the problem may be do to a recent upgrade to El Capitan.