Hello webkit-dev,
In summary: this is a feature that allows authors and users to craft URLs to pages and specify a snippet of text on the page as a subresource (visually highlighting it and scrolling it into view). Analogous to element-id based fragment anchors but for text.
Relevant Links:
We've been using the GitHub repo for issue tracking but happy to take feedback (official or otherwise) in any form.
Thank you!
David