Use dump-as-markup.js in editing/selection/user-select-all-selection.html instead of manually asserting offsets, etc...
Pull request: https://github.com/WebKit/WebKit/pull/6605
Committed 256818@main (a8b85bf8a613): <https://commits.webkit.org/256818@main> Reviewed commits have been landed. Closing PR #6605 and removing active labels.
<rdar://problem/102498439>