[8u] RFR 8027154: [TESTBUG] Test java/awt/Mouse/GetMousePositionTest/GetMousePositionWithPopup.java fails

[Zhengyu Gu]

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

The original bug: https://bugs.openjdk.java.net/browse/JDK-8027154
patch: http://hg.openjdk.java.net/jdk10/jdk10/jdk/rev/59b6ea076972


The original patch does not apply cleanly, but only conflict is @bug 
line, due to 8u does not "@key headful" line above (JDK-8160974, still 
not yet pushed)


8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8027154-8u/webrev.00/

Test:
   The test passed on Linux x86_64

Thanks,

-Zhengyu