Fix problem with rule calculation

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@5296 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rdoc/markup/simple_markup/to_flow.rb

@@ -89,6 +89,8 @@ module SM
     end
 
     def accept_rule(am, fragment)
+      size = fragment.param
+      size = 10 if size > 10
       @res << Rule.new(size)
     end