[8u] RFR 8004148: NPE in sun.awt.SunToolkit.getWindowDeactivationTime

[Zhengyu Gu]

I would like to backport this patch to openjdk8u for parity with Oracle 
8u301.

Bug: https://bugs.openjdk.java.net/browse/JDK-8004148
Patch: http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/29b0423db43c

The original patch does not apply cleanly, due to different context, can 
be easily resolved manually.

8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8004148-8u/webrev.00/

Thanks,

-Zhengyu