Bug 243488

I find an unexpected result when I created an iframe in my code, but it affected promise microtasks in webkit.eg: safari，iosApp webview.

code:
Promise.resolve(1).then(data => {
  console.log('>>>data')
})

var node = document.createElement('iframe')
node.style.display = 'none'

node.src = 'www.baidu.com';
(document.body || document.documentElement).appendChild(node)
console.log('>>>end')


It‘s normal output is：
>>>end
>>>data

But it‘s output in webkit is：
>>>data
>>>end