Revert "Fix zero division when the screen width is not available"

This reverts commit 0dce9da.

lib/reline/line_editor.rb

@@ -340,8 +340,7 @@ def multiline_off
   end
 
   private def calculate_height_by_width(width)
-    max_width = @screen_size.last
-    max_width > 0 ? (width.div(max_width) + 1) : 1
+    width.div(@screen_size.last) + 1
   end
 
   private def split_by_width(str, max_width)