Add spec for webview visibility change on show

spec/webview-spec.js

@@ -1097,6 +1097,30 @@ describe('<webview> tag', function () {
     })
   })
 
+  describe('document.visibilityState/hidden', function () {
+    afterEach(function () {
+      ipcMain.removeAllListeners('pong')
+    })
+
+    it('updates when the window is shown after the ready-to-show event', function (done) {
+      w = new BrowserWindow({
+        show: false
+      })
+
+      w.once('ready-to-show', function () {
+        w.show()
+      })
+
+      ipcMain.on('pong', function (event, visibilityState, hidden) {
+        if (!hidden) {
+          assert.equal(visibilityState, 'visible')
+          done()
+        }
+      })
+
+      w.loadURL('file://' + fixtures + '/pages/webview-visibilitychange.html')
+    })
+
     it('inherits the parent window visibility state and receives visibilitychange events', function (done) {
       w = new BrowserWindow({
         show: false
@@ -1117,6 +1141,7 @@ describe('<webview> tag', function () {
 
       w.loadURL('file://' + fixtures + '/pages/webview-visibilitychange.html')
     })
+  })
 
   describe('will-attach-webview event', () => {
     it('supports changing the web preferences', (done) => {