ticket:11100: fix crash happening when there are many nested matching parentheses occurring in more than one paragraph.
Also change terminology from xxx_SIZE to xxx_COUNT to pursue change started in ticket #11054.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@36557 251d0590-4201-4cf1-90de-194747b24ca1