Can't waitForSelector if the selector contains :focus or something else exotic

[JoelEinbinder]

When we do waitForSelector, we poll on DOM mutations. But some things that can change the selectors an element matches against aren't DOM mutations. For example:

const focusedButtonPromise = page.waitForSelector('button:focus');
await page.focus('button');
// times out, because focus doesnt trigger a DOM mutation.
const focusedButton = await focusedButtonPromise; 

Would also effect

• :focus-within
• :active
• :hover
• :visited (currently broken for other reasons)
• :empty
• :valid

Maybe others.

I don't really want to wait on focus changes or value changes for every waitForSelector. Maybe a quick hack that also waits on rafs when the selector contains ":"?

[dgozman]

We are not going to support pseudo states in waitForSelector.