Add a test of yield yield yield... chains.
Add a test of yield yield yield... chains.

juliocanares/regenerator,facebook/regenerator,facebook/regenerator,jlongster/transmogrifier,sebmck/regenerator,liviuignat/regenerator,juliocanares/regenerator,jlongster/transmogrifier,jlongster/unwinder,RReverser/js-goto-transpiler,rafaelstz/regenerator,Jericho25/regenerator,kittens/regenerator,rafaelstz/regenerator,facebook/regenerator,liviuignat/regenerator,kittens/regenerator,RReverser/js-goto-transpiler,Jericho25/regenerator,jlongster/unwinder,rwaldron/regenerator,jlongster/unwinder,sebmck/regenerator