[xhr] "relative flag" outdated terminology? (#44)

"open() method" step 9:

> If parsedURL's [relative flag](https://url.spec.whatwg.org/#relative-flag) is set, run these substeps: 

Seems this definition is gone from the URL spec, there's a "not relative flag" instead.

@annevk ?

---
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/xhr/issues/44