Make ChannelIterator.next non-suspending

[qwwdfsad]

State machine allocation in ChannelIterator.next is, in fact, unnecessary as hasNext suspends and consumes an element from the channel anyway. Suspension in next was introduced to have shortcuts for operators like first that do not call hasNext at all.
The key point here is to make a binary compatible change

[fvasco]

Hi @qwwdfsad,
maybe you have to update the documentation, also.
There is no mention to the hasNext method there, so the follow ugly example is licit :

fun main() = runBlocking {
    val channel = produce {
        repeat(3) {
            send(it)
            delay(10)
        }
    }
    val iterator = channel.iterator()
    repeat(3) {
        val i = iterator.next()
        println(i)
    }
}

[elizarov]

@fvasco Good catch. Docs will have to be updated, too.