fix: treat CSS attribute selectors as case-insensitive for HTML enumerated attributes#17712

Rich-Harris merged 3 commits intosveltejs:mainsveltejs/svelte:mainfrom

veeceey:fix/issue-17207-css-attribute-case-insensitiveveeceey/svelte:fix/issue-17207-css-attribute-case-insensitiveCopy head branch name to clipboard