Fix e2e test for ESM. (#211)

Author: jsonnull

examples/basic-vanilla-esm/index.e2e.js

@@ -15,6 +15,7 @@ test('Hello Electron', async () => {
   });
 
   const window = await electronApp.firstWindow();
+  await window.waitForEvent('load');
   expect(await window.title()).toBe('Hello from Electron renderer!');
 
   const response = await window.textContent('[data-testid="greeting"]');