RFR (S): 8056911: Remove internal API usage from ExtendedRobot class

[Hohensee, Paul]

This is actually a pair of backports. After 8056911, 8062606 was needed to fix 8056911.

This pair was pushed to IcedTea, see http://icedtea.classpath.org//hg/icedtea8-forest/jdk?cmd=changeset;node=96efd35f030e<http://icedtea.classpath.org/hg/icedtea8-forest/jdk?cmd=changeset;node=96efd35f030e>.

JBS issue: https://bugs.openjdk.java.net/browse/JDK-8056911
Original patch: http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/c6b695f708f1
8u webrev: http://cr.openjdk.java.net/~phh/8056911/webrev.8u.jdk.00/

The patch applied cleanly net of file location and context.

JBS issue: https://bugs.openjdk.java.net/browse/JDK-8062606
Original patch: http://hg.openjdk.java.net/jdk9/jdk9/jdk/rev/7afec3ed5ab5
8u webrev: http://cr.openjdk.java.net/~phh/8062606/webrev.8u.jdk.00/

The patch applied cleanly after 8056911.

Thanks,
Paul