Fix webview resize test

spec/webview-spec.js

@@ -1482,11 +1482,18 @@ describe('<webview> tag', function () {
 
       webview.addEventListener('resize', function onResize (event) {
         webview.removeEventListener('resize', onResize)
+        assert.equal(event.newWidth, 100)
+        assert.equal(event.newHeight, 10)
+        assert.equal(event.target, webview)
+        webview.addEventListener('resize', function onResizeAgain (event) {
+          // This will be triggered after setting the new div width and height.
+          webview.removeEventListener('resize', onResizeAgain)
           assert.equal(event.newWidth, 1234)
           assert.equal(event.newHeight, 789)
           assert.equal(event.target, webview)
           done()
         })
+      })
 
       webview.src = `file://${fixtures}/pages/a.html`
       div.appendChild(webview)