Verify that bare .java plugins see the correct macro options

This is essentially a dramatically shrunk-down version of the problem
described by Aryeh Weiss in http://fiji.sc/bugzilla/show_bug.cgi?id=787
-- bare .java plugins, or for that matter, all non-macro scripts
did not see the correct macro options anymore.

The problem has been fixed with the commit 'DefaultLegacyHooks: use
ThreadService to implement getThreadAncestors()' and this regression
test will ensure that users won't see the problem again.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>