cannot get iframe element in youtube page

[dinggewennuan]

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 2.1.1
• Platform / OS version: macOS High Sierra 10.13.6
• URLs (if applicable): https://www.youtube.com/channel/UC-3fLOkTRb7-tepOqxsDdDg/about
• Node.js version:8.11.4

What steps will reproduce the problem?
i want got email in this page,but when i clicked VIEW EMAIL ADDRESS ，the page insert a new iframe,but i can got it used every ways

Please include code that reproduces the issue.

`async function test2 () {
const browser = await puppeteer.launch({
headless: false,
devtools: true,
defaultViewport: {
height: 1024,
width: 1280
}
})

const page = await browser.newPage();

await page.goto('https://www.youtube.com/channel/UC-3fLOkTRb7-tepOqxsDdDg/about', {
    timeout: 0,
    waitUntil: 'networkidle0'
})
try {        
     await page.click('#details-container > table > tbody > tr:nth-child(1) > td:nth-child(2) > ytd-button-renderer > a')

    let iframes = await page.frames()
    // console.log("iframe  ", iframes)
    // await page.waitForSelector("#recaptcha-anchor")
    // await page.waitForSelector('#captcha-container iframe');
    // await page.waitForSelector('#captcha-container > form > button'
    let iframe = await page.frames().find(f => f.name())
   // cannot got everything
    for (const frame of page.mainFrame().childFrames()) {
        console.log("url is", frame.url(), frame.title())
        console.log("-------name------",frame.name())
    }
    
    await page.close();
    await browser.close();
    console.log("end--------------")
} catch (error) {
    console.log("error is ", error)
}

}`
What is the expected result?
i hope got the final email

What happens instead?

[devjerry]

check out #4960

[stale]

We're marking this issue as unconfirmed because it has not had recent activity and we weren't able to confirm it yet. It will be closed if no further activity occurs within the next 30 days.

[stale]

We are closing this issue. If the issue still persists in the latest version of Puppeteer, please reopen the issue and update the description. We will try our best to accomodate it!