Add failing spec for sandboxed window.open

spec/static/main.js

@@ -245,3 +245,8 @@ ipcMain.on('create-window-with-options-cycle', (event) => {
   const window = new BrowserWindow({show: false, foo: foo})
   event.returnValue = window.id
 })
+
+
+ipcMain.on('prevent-next-new-window', (event, id) => {
+  webContents.fromId(id).once('new-window', event => event.preventDefault())
+})