Relates to issue #28160

Go1 spec allows for 2 different return statement styles causing unnecessary added complexity and confusion for some developers.

Using an example func from the spec:

func complexF3() (re float64, im float64) {
	re = 7.0
	im = 4.0
	return
}
// vs
func complexF3() (re float64, im float64) {
	re = 7.0
	im = 4.0
	return re, im
}

This proposal is to remove implicitly returned result parameters from the spec, thereby requiring result parameters to always be explicitly returned.