fix

src/compile/render-dom/wrappers/Window.ts

@@ -182,6 +182,8 @@ export default class WindowWrapper extends Wrapper {
 				`@listen(window, "online", ctx.${handler_name})`,
 				`@listen(window, "offline", ctx.${handler_name})`
 			);
+
+			component.has_reactive_assignments = true;
 		}
 	}
 }

test/js/samples/bind-online/expected.js

@@ -33,7 +33,7 @@ function create_fragment(ctx) {
 	};
 }
 
-function instance($$self) {
+function instance($$self, $$props, $$invalidate) {
 	let online;
 
 	function onlinestatuschanged() {