Add user activation set to bounce tracking record

[amaliev]

Adding a set of all sites that received an interaction during this extended navigation.

This isn't necessary within this spec but will be referenced by heuristics (whatwg/compat#253) to determine which sites are eligible for the redirect heuristic. Note that the appending flow is intentionally different for the initial host and bounced hosts - in the former case we need to wait for the bounce tracking record to be created when the next navigation starts.

Closes #67

---

Preview | Diff

[wanderview]

Rather than adding this here, I think we should keep it with the heuristics spec and monkey patch the core specs. There is no strict reason to have a dependency between bounce tracking and heuristics, so we should probably avoid it.

[wanderview]

Rather than adding this here, I think we should keep it with the heuristics spec and monkey patch the core specs. There is no strict reason to have a dependency between bounce tracking and heuristics, so we should probably avoid it.

Thinking about this more, I think it would be fine to add here for now, but with a note that the redirect logic should be factored out into a common algorithm used by multiple features. This might be easier to do once the spec is upstreamed in the html spec, etc.

[jyasskin]

You might also be able to upstream the redirect logic before the rest of the spec, if it's more-clearly useful to a spec that's already in the WHATWG.