LP:727183 - WL#90 does not trigger with non-comma joins

WL#90 optimizations only trigger for comma joins. They do not trigger for any other join type, and they do not trigger if ON or USING clause is used.

Queries provided by spetrunia:

(15:37:04) spetrunia: MariaDB [test]> explain select * from one_k_key X, ten Y where X.a in (select max(a) from ten);
(15:37:06) spetrunia: this works
(15:37:12) spetrunia: MariaDB [test]> explain select * from one_k_key X join ten Y on X.a < Y.a where X.a in (select max(a) from ten);
(15:37:19) spetrunia: this doesn't