By escaping self to HTML, how many more bytes will be needed ?

Property definitions

core :: flat $ FlatText :: chars_to_html_escape
	# By escaping `self` to HTML, how many more bytes will be needed ?
	fun chars_to_html_escape: Int do
		var its = _items
		var max = last_byte
		var pos = first_byte
		var endlen = 0
		while pos <= max do
			var c = its[pos]
			if c == u'<' then
				endlen += 3
			else if c == u'>' then
				endlen += 3
			else if c == u'&' then
				endlen += 4
			else if c == u'"' then
				endlen += 4
			else if c == u'\'' then
				endlen += 4
			else if c == 0x2F then
				endlen += 4
			end
			pos += 1
		end
		return endlen
	end
lib/core/text/flat.nit:108,2--132,4