case-sensitivity of SVG viewBox likely to cause silent errors

[lnryan]

In most 'try online' tools, the SVG viewBox attribute is handled the same whether properly camel-cased or not (viewbox). Svelte only recognizes viewBox. This can make it difficult for developers new to SVG - especially when they are starting with random sample code from blogs/tutorials - as improper use simply doesn't show up. Either an compile-time warning or acceptance of both variants would be helpful.

Example:
When I try to render <svg viewbox="-250 -250 500 500"> with the Svelte, my image is cutoff. Whereas on W3Schools or CodePen, it renders fine, indicating that width and height aren't inherently mandatory. I had the same results testing locally and with REPL.

When I try <svg width=500 height=500 viewbox="-250 -250 500 500"> it will adjust the size correctly, but doesn't respect the viewbox.

Since I started with pasting a blog example, I mistakenly thought svelte couldn't handle viewbox.

[Conduitry]

I take it from what's been said on the closed PR #1077 that what we'd want to do is lowercase all of the attribute names in HTML, and to lowercase SVG ones, apart from those with mixed case here and to instead make those conform to the case in that list?

[Rich-Harris]

Yep, exactly — have raised #1095 to that end

[Rich-Harris]

This is fixed in 1.52, thanks