[css2] Edited issue

http://www.w3.org/Style/css2-updates/REC-CSS2-20110607-errata.html#s.11.1.1
about 'overflow'

--HG--
extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%403260

Author: bert-github

css2/properties/properties.db

@@ -351,7 +351,7 @@ table-cell | table-caption | none | inherit;;
 /* overflow;;
   visible | hidden | scroll | auto | inherit;;
   visible;;
-  block containers;;
+  block containers and boxes that establish a formatting context;;
   no;;
   N/A;;
   visual;;