[9] Review Request for 8079595: Resizing dialog which is JWindow parent makes JVM crash

[Semyon Sadetsky]

Hello,

Please review fix for JDK9:
bug: https://bugs.openjdk.java.net/browse/JDK-8079595
webrev: http://cr.openjdk.java.net/~ssadetsky/8079595/webrev.00/
Direct call to DefWindowProc() of the child window's owner causes a 
conflict. Using SendMessage() eliminates it.

--Semyon