Created attachment 174474 [details]
Screenshot of news.ycombinator.com comments
Text Autosizing poorly handles nested comment lists on sites like news.ycombinator.com.
See attached screenshot of news.ycombinator.com comments.
Ideally, all the comments would end up with the same font size. But each comment is wrapped in a table cell (td), and the table cells each trigger a new cluster (see bug 97025). Clusters independently determine whether they contain enough text to bother autosizing at all (hence short comments don't get multiplied, but long comments do), and those clusters that do perform autosizing then independently determine their text autosizing multiplier based on their width, hence amongst the comments that get autosized the more deeply nested ones (which are narrower) get a smaller multiplier.
Ultimately clustering needs to be smarter about tables.
Marking this bug Resolved WontFix because the TEXT_AUTOSIZING feature was removed in <https://trac.webkit.org/changeset/206119> (bug #162167). See bug 84186, comment 32 for more details.