Make vertical-align text-top/bottom more CSS 2.1 compliant: we are looking for the parent's font or font strut's *content area* (as per 10.6.1) so do not use its baselinePosition.

Add the missing half-leading for both text-top and text-bottom (mozilla/css_1/vertical_align_texttop.html): that's also part of content area.

Using baselinePosition on parent was even more bogus because of the major semantic differences in CSS between baseline in table context and other baselines. A mess that was the origin of #103039