Created attachment 174757 [details]
Screenshot of flickr.com heading
Some sites set the line-height smaller than the font-size on single-line headings, as an alternative way of reducing the heading's top/bottom margins.
When these single-line headings are autosized, if they wrap onto more than one line the line spacing between the lines will be insufficient.
For example the "Share your photos with your friends and family" heading on the attached screenshot has font-size:30px but line-height:20px, hence the top of the 'f' risks overlapping the bottom of the 'y' (much worse examples are possible!).
Text Autosizing should make sure that whenever single-line text is made to wrap onto multiple lines, the intra-line spacing is always at least ~1em (ideally this would be done without affecting the margins implied by the line height).
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.