Modified WillMakeList() to clear prevListItem after adding a block
to a list item so that any inline nodes after the block are put
in a new list item.
r=jfrancis@netscape.comsr=sfraser@netscape.com
git-svn-id: svn://10.0.0.236/trunk@107105 18797224-902f-48f8-a5cc-f745e15eee43