なんかもうめっちゃ変えた

src/web/app/common/scripts/contains.ts

@@ -0,0 +1,8 @@
+export default (parent, child) => {
+	let node = child.parentNode;
+	while (node) {
+		if (node == parent) return true;
+		node = node.parentNode;
+	}
+	return false;
+};