COOP Reporting: typo ancestor -> accessor

[zcorpan]

https://html.spec.whatwg.org/multipage/origin.html#reporting

If accessor's active document's origin or any of its ancestors' active document's origins are not same origin with ancestor's top-level browsing context's active document's origin, or if accessed's active document's origin or any of its ancestors' active document's origins are not same origin with accessed's top-level browsing context's active document's origin, then return.

ancestor is not a defined variable, I assume accessor was meant.