RfA backport of JDK-8078408

[Pete Brunet]

I'd like to backport JDK-8078408 from 9 to 8u.  The 8u bug is JDK-8079828.

This is a simple patch to add a null check to eliminate an NPE.

https://bugs.openjdk.java.net/browse/JDK-8078408  // 9 bug
https://bugs.openjdk.java.net/browse/JDK-8079828  // 8u bug
http://hg.openjdk.java.net/jdk9/client/jdk/rev/0c2a21066609
http://mail.openjdk.java.net/pipermail/awt-dev/2015-May/009347.html

Due to the different file structure from 9 to 8u the patch would not
apply cleanly but after making the same change the patch builds clean
locally and on JPRT and tests clean.

Pete