[css-inline-3] Issues for Discussion

Hi everyone,
I've spent the last couple weeks working through the CSS Inline Layout issues.
There's a few that seem ready for CSSWG discussion.

Line Layout

1. Move top|bottom|center values from alignment-baseline to baseline-shift
    https://github.com/w3c/csswg-drafts/issues/5180

2. Defining the central baseline
    https://github.com/w3c/csswg-drafts/issues/5177

3. Rethinking line-sizing and leading-trim
    https://github.com/w3c/csswg-drafts/issues/5168

3. line-height < 1 in a margin-box line layout model
    https://github.com/w3c/csswg-drafts/issues/5178

4. vertically align to nth-child
    https://github.com/w3c/csswg-drafts/issues/1339

5. 'line-height: normal' definition should reflect reality
    https://github.com/w3c/csswg-drafts/issues/1254#issuecomment-641716202

6. naming of text-top and text-bottom baselines
    https://github.com/w3c/csswg-drafts/issues/860
    Suggest to close no-change given history...

Initial Letter Layout

1. [css-inline-3] initial-letters changing used, not computed font-size
    https://github.com/w3c/csswg-drafts/issues/4988

2. initial-letters-wrap: first, whitespace collapse needs defining
    https://github.com/w3c/csswg-drafts/issues/5120

3. initial-letters: interaction of shape-margin and regular margin
    https://github.com/w3c/csswg-drafts/issues/5119

Saving some bikeshedding for last:

1. inline-sizing property name is too similar to inline-size
    https://github.com/w3c/csswg-drafts/issues/5189

Additionally, I've gone ahead and properly integrated the vertical-align and 
line-height calculation rules from CSS2.1 into the spec. You can see the new 
text in
   Chapter 2: Inline Layout Model
     https://drafts.csswg.org/css-inline-3/#model
   Chapter 3: Baselines and Alignment Metrics
     https://drafts.csswg.org/css-inline-3/#css-metrics
   Section: Logical height Contributions of Inline Boxes
     https://drafts.csswg.org/css-inline-3/#inline-height
I haven't integrated the 'leading-trim' or 'line-sizing: normal' proposals 
into the line height calculation sections; would people prefer to review the 
text before or after doing so?

~fantasai