[css-ruby] Issues with ruby sizing in block direction

A few issues with ruby sizing in the block direction, the first of
which was discussed in a side discussion after the face-to-face
meeting today (in which other issues were discussed):

 (1) http://dev.w3.org/csswg/css-ruby/#ruby-layout says "Each ruby
 base container is sized and positioned to contain exactly all of
 its ruby bases’ margin boxes.".  This presumes that the ruby bases
 have known positions, which isn't true, since vertical alignment
 (particularly for 'top' and 'bottom') can't be done until layout of
 the entire line is complete.  The simple solution is to say that
 vertical-align does not apply to ruby bases (they're always like
 'baseline'), and to say that their block-direction size is computed
 as for inlines (based on the font, not contents).

 (2) It also says "Ruby annotation containers are stacked outward
 over or under their corresponding ruby base container, without any
 intervening space.".  This doesn't say what edges are stacked,
 though I'm guessing it means margin edges.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)