Bug 989204 part 1 - Add some arrow function tests. r=jorendorff

--HG--
extra : rebase_source : 0b3c9ddd82621fd76e7d48559f339cdea6c40a76
Bug 989204 part 2 - Don't use bound functions for arrow functions. r=jorendorff,bhackett

--HG--
extra : rebase_source : a730255b4f3458465272fe1ee8ab9724f68af723