Ensure a non-empty tab's URL value (#6154)
Ensure a non-empty tab's URL value (#6154)

* Ensure a non-empty tab's URL value

- Ensure that we have a "default value" for tab.url so legit pages will still handle correctly.
- Because of this behavior only happens on `about:blank`-like pages we simply use that as value.
- Resolves #6151

* Fix comment placement

* Use `tab` as argument
alexanderby/darkreader,darkreader/darkreader,darkreader/darkreader,alexanderby/darkreader,darkreader/darkreader,alexanderby/darkreader