Bug 839809:  Make counter-increments and list counting that would go past our internal (int32_t) limit keep the counter at its current value rather than wrapping.  r=dholbert

Per CSS WG resolution regarding counter-styles-3, afternoon of 2013-02-05:
http://krijnhoetmer.nl/irc-logs/css/20130205#l-1590
http://lists.w3.org/Archives/Public/www-style/2013Feb/0392.html