Inline size: remove 'number' value.

[Tavmjong]

Fixes #436

[ewilligers]

Why isn't auto supported?

[Tavmjong]

What would be the 'auto' value?

[ewilligers]

We seem to have SVG and CSS defining inline-size in conflicting ways.

https://drafts.csswg.org/css-logical/#propdef-inline-size
supports 'auto' and has 'auto' as the initial value.

What would be the 'auto' value?

Discussed for HTML in https://www.w3.org/TR/CSS21/visudet.html#propdef-width

Perhaps the SVG spec needs to discuss it too.

I don't think we have any browser implementations following the SVG grammar. Blink supports 'auto' and has 'auto' as the initial value.

[AmeliaBR]

@ewilligers Can you make a separate issue for this, since this PR has now been merged? auto should be allowed, and should be the default value, meaning do not constrain the inline size at all. Although that brings up the question of what the computed value should be: the text length, I guess.

There should maybe also be a note that says that the definition in CSS Logical Properties will supersede the SVG-specific one, when that spec is finalized.