Doesn't mahāyāna have a classification for jhānas?
You're right - jhanas are deemphasized (and for good reason as far as I'm concerned), but don't forget that most Mahayana schools use the Chinese Agamas as a part of their canonical literature.  The Agamas do contain, more or less, the original Sutta-pitaka along with the vinaya, abhidhamma, etc.  You're not finding anything in the newer Mahayana literature because the Mahayanists are just using a Chinese translation of the same texts a Theravadan might refer to.