Because Watir does not yet support font tag, you will have to extend it.
Fortunately, that is easy. Add code at the top of your script.:
module Watir
class Font < NonControlElement
TAG = 'font'
end
module Container
def font(how, what)
return Font.new(self, how, what)
end
end
end

And now Watir knows all about fonts!

ie.font(:text, "(+)").click