Implement line numbers without the Liquid::Token class.

lib/liquid/errors.rb

@@ -17,12 +17,6 @@ module Liquid
       str
     end
 
-    def set_line_number_from_token(token)
-      return unless token.respond_to?(:line_number)
-      return if line_number
-      self.line_number = token.line_number
-    end
-
     def self.render(e)
       if e.is_a?(Liquid::Error)
         e.to_s