[js] Dce removes static field with function call

[RblSb]

class Main {
	static final numbers = [];
	static function addNum(n:Int):Int {
		numbers.push(n);
		return n;
	}
	static final node = addNum(1);

	static function main() {
		trace(numbers.length); // 0
	}
}

Fine on eval.

[Simn]

Hmm, I vaguely remember that this is by design, but looking at it now makes me question if that design is any good...

[back2dos]

As mentioned in #10766, I think ideally purity would be taken into account here.