There’s a subgenre of teen rom-coms that modernize everything from William Shakespeare to Jane Austen. On Hulu, the movie “Rosaline” flips that idea back around, giving modern rom-com tropes and dialogue to the original 16th-century setting of Shakespeare’s “Romeo and Juliet.” I mean, why not? Well, for one: The play ends in tragedy! Screenwriters Scott Neustadter and Michael H. Weber (who previously teamed up on 2017′s “The Disaster Artist”) get around that by focusing not on the two star-crossed lovers of the Houses Capulet and Montague, but on Juliet’s cousin Rosaline (Kaitlyn Dever). The o…