Require: add_index < length

Property definitions

glesv2 $ GLfloatArray :: add
	# Require: `add_index < length`
	fun add(value: Float)
	do
		var index = add_index
		assert index < length
		native_array[index] = value
		self.add_index = index + 1
	end
lib/glesv2/glesv2.nit:455,2--462,4