[css-inline-3] Shift top | bottom | center values from alignment-baseline to baseline-shift #5180

In trying to harmonize CSS and SVG, we made the SVG alignment-baseline and baseline-shift longhands of CSS’s vertical-align property. Overall this seems to work pretty well, but I put the top and bottom (and the corresponding new center value) under alignment-baseline, but I'm wondering if maybe they're a better fit under baseline-shift? They don't exactly specify a baseline, and at least in CSS2 they were mutually exclusive with a shift value.