Uncomment exec test code after https://github.com/babel/babel/pull/7687 and https://github.com/babel/babel/pull/7691 are both merged. - https://github.com/babel/babel/pull/7691/files#diff-74aa110163670429a0674498e3bc6830R14 - https://github.com/babel/babel/pull/7691/files#diff-ca58a909f06bc6a60ca393eb9d8c75ddR14