Return true if `self` IS `o` (using the Nit semantic of is)

Property definitions

	# Return true if `self` IS `o` (using the Nit semantic of is)
	fun eq_is(o: Instance): Bool do return self.is_same_instance(o)

src/interpreter/naive_interpreter.nit:727,2--728,64

	redef fun eq_is(o)
	do
		if not o isa PrimitiveInstance[nullable Object] then return false
		return self.val.is_same_instance(o.val)
	end

src/interpreter/naive_interpreter.nit:820,2--824,4