Use `event.key` in tests instead of deprecated event.which

test/runtime/samples/action-custom-event-handler-this/_config.js

@@ -4,7 +4,7 @@ export default {
 	test({ assert, component, target, window }) {
 		const input = target.querySelector('input');
 		const event = new window.KeyboardEvent('keydown', {
-			which: 13
+			key: 'Enter'
 		});
 
 		let blurred = false;

test/runtime/samples/action-custom-event-handler-this/main.svelte

@@ -1,7 +1,7 @@
 <script>
 	function enter(node, callback) {
 		function handleKeydown(event) {
-			if (event.which === 13) {
+			if (event.key === 'Enter') {
 				callback(event);
 			}
 		}

test/runtime/samples/window-event-custom/_config.js

@@ -3,7 +3,7 @@ export default {
 
 	async test({ assert, component, target, window }) {
 		const event = new window.KeyboardEvent('keydown', {
-			which: 27
+			key: 'Escape'
 		});
 
 		await window.dispatchEvent(event);

test/runtime/samples/window-event-custom/main.svelte

@@ -3,7 +3,7 @@
 
 	function esc(node, callback) {
 		function onKeyDown(event) {
-			if (event.which === 27) callback(event);
+			if (event.key === 'Escape') callback(event);
 		}
 		node.addEventListener('keydown', onKeyDown);
 		return {