Prevent top navigations without user activation in some circumstances?

[domenic]

I'm still investigating exactly what is going on here, but between WICG/interventions#16 and https://chromestatus.com/feature/5851021045661696 there is some indication that Chrome shipped a restriction on how much iframes can navigate the top-level frame, beyond the currently-specified restrictions based on sandboxing.

I have found some evidence that:

• This is based on sticky activation, not transient activation
• Something changed in Chrome 102 which is causing people to notice this now; possibly something about resetting sticky activation on redirects

Supposedly Chrome shipped this in Chrome 68, but every few releases someone shows up in WICG/interventions#16 complaining that something new is broken, so it's not clear exactly what Chrome is doing here.

We should:

• Figure out exactly what Chrome has implemented
• See if other browsers are interested in doing so as well
• If so, spec it and write WPTs.

/cc @natechapin @shivanigithub