RFR: 8088395: Print dialogs are not blocking/modal w.r.t specified owner windows

[Phil Race]

This is the 8u backport of this FX+JDK fix

Not much changed so not much re-review is needed.

First the FX part.

https://bugs.openjdk.java.net/browse/JDK-8088395

webrev : http://cr.openjdk.java.net/~prr/8088395.8u/

The patch applied cleanly but the fix needed some small updates.

In JDK 9 we used

final TKStage stage = WindowHelper.getPeer(owner);

In JDK 8 that helper does not (need to) exist as we still have the impl 
methods
so it looks like

final TKStage stage = owner.impl_getPeer();


Also in J2DPrinterJob.java I was able to remove (old lines 105-110)
a condition which requested that asking for the native dialog be
skipped on Linux. The JDK bug which required that workaround has
now been backported.


On the JDK side no changes were needed, no backport review requested
but here are the changes which will be needed by anyone who wants to
test it:

https://bugs.openjdk.java.net/browse/JDK-8176530

http://cr.openjdk.java.net/~prr/8176350.8u/

-phil.