Add a test of nested catch blocks causing the transformer to abort.
Add a test of nested catch blocks causing the transformer to abort.

As reported by @radford in #56.

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