Provide EventSource.asFlow extension

[qwwdfsad]

Open questions:

• How to handle backpressure by default? Should we use a conflated channel or an unlimited one?
• Can multiple flows be constructed from the single EventSource?

[sdeleuze]

I will think about those questions.

Since my use case of EventSource is pretty anectdotical, I would suggest to turn this issue into a more global one like "Provide suspending function and Flow based extensions on top of Web APIs".

The more I use Kotlin/JS, the more I think you could do for frontend what you did on Android with carefully crafted Kotlin extensions on top of Web APIs.

[sdeleuze]

Another example using suspending functions:

suspend fun Window.awaitLoad() = suspendCoroutine<Unit> { cont ->
    onload = {
        cont.resume(Unit)
    }
}

[LouisCAD]

I'd prefer to support cancellation:

suspend fun Window.awaitLoad() {
    try {
        suspendCancellableCoroutine<Unit> { cont ->
            onload = {
                onload = null
                cont.resume(Unit)
            }
        }
    } finally {
        onload = null
    }
}

[LouisCAD]

Even if in the case of waiting for window loading, cancellation is unlikely at this point, it might help some coroutines being cancelled earlier if the case applies.