[9] Review request for 8033069: mouse wheel scroll closes combobox popup

[Alexey Ivanov]

Hello Swing team,

Could you please review the fix:
    bug: https://bugs.openjdk.java.net/browse/JDK-8033069
    webrev: http://cr.openjdk.java.net/~aivanov/8033069/jdk9/webrev.00/
Description:
If you rotate mouse wheel when combo box popup is open, the popup gets 
closed.

The fix is to always consume MOUSE_WHEEL event.

There are two regression tests for the cases where popup has vertical 
scroll bar and does not have scroll bar.

Thanks,
Alexey