[10] Review request for 8182638: [macosx] Active modal dialog is hidden by another non-active one

[Semyon Sadetsky]

Hello,

Please review fix for JDK10:
bug: https://bugs.openjdk.java.net/browse/JDK-8182638

webrev: http://cr.openjdk.java.net/~ssadetsky/8182638/webrev.00/

Since 8169589 sibling windows are ordered above the parent. It requires 
for the new active child windows to be raised above  its siblings not 
only above its parent window.

--Semyon