test: make before-input-event test more robust

spec/api-web-contents-spec.js

@@ -159,17 +159,16 @@ describe('webContents module', () => {
 
   describe('before-input-event event', () => {
     it('can prevent document keyboard events', (done) => {
-      w.loadFile(path.join(fixtures, 'pages', 'key-events.html'))
-      w.webContents.once('did-finish-load', () => {
       ipcMain.once('keydown', (event, key) => {
         assert.strictEqual(key, 'b')
         done()
       })
-
+      w.webContents.once('did-finish-load', () => {
-        ipcRenderer.send('prevent-next-input-event', 'a', w.webContents.id)
+        ipcRenderer.sendSync('prevent-next-input-event', 'a', w.webContents.id)
         w.webContents.sendInputEvent({ type: 'keyDown', keyCode: 'a' })
         w.webContents.sendInputEvent({ type: 'keyDown', keyCode: 'b' })
       })
+      w.loadFile(path.join(fixtures, 'pages', 'key-events.html'))
     })
 
     it('has the correct properties', (done) => {

spec/static/main.js

@@ -212,6 +212,7 @@ app.on('ready', function () {
     webContents.fromId(id).once('before-input-event', (event, input) => {
       if (key === input.key) event.preventDefault()
     })
+    event.returnValue = null
   })
 
   ipcMain.on('executeJavaScript', function (event, code, hasCallback) {