[8u] RFR 8196093: javax/swing/JComboBox/8072767/bug8072767.java fails

[Zhengyu Gu]

I would like to backport this patch to 8u. This patch fixes test failure 
of 8u parity backport JDK-8072767

The original bug: https://bugs.openjdk.java.net/browse/JDK-8196093
The original patch: https://github.com/openjdk/jdk/commit/513269d2

The backport is mostly clean, except the test is not in 8u's ProblemList.

8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8196093-8u/webrev.00/

The patch contains JDK-8072767 as this patch is followup fix of 
JDK-8072767 and I expect to push them together once approved.

Test:
   Passed tests in patch.

Thanks,

-Zhengyu