Sort result of lexer.parse by pos in ruby<2.7. It's not sorted when t…

…he given code includes heredoc.

lib/irb/ruby-lex.rb

@@ -167,7 +167,7 @@ def self.ripper_lex_without_warning(code, context: nil)
           end
         end
       else
-        tokens = lexer.parse.reject { |it| it.pos.first == 0 }
+        tokens = lexer.parse.sort_by(&:pos).reject { |it| it.pos.first == 0 }
       end
     end
     tokens