Optimize sub-graphs that have no suspension point

[Simn]

Given this:

import haxe.coro.Coroutine;

@:coroutine @:coroutine.debug function f() {
	Coroutine.yield();
	if (Math.random() > 0.5) {
		trace(">");
	} else {
		trace ("<");
	}
	Coroutine.yield();
}

function main() {
	Coroutine.run(f);
}

We get this CFG:

The sub-graph consisting of nodes 1, 2, 3 and 4 can be folded to a single state by using a normal if. I'll have to remember some graph theory in order to detect this accurately.