[dom] How looks converting a string to ASCII uppercase/lowercase for other Unicode characters? (#159)

Whe have two def:
https://domspecwhatwgorg/#converted-to-ascii-uppercase
https://domspecwhatwgorg/#converted-to-ascii-lowercase
but it only covers ASCII characters What should be done if we use in some methods other characters, like Ś, Ź, Ć Ż, etc?

For example, "converted to ASCII lowercase" is used in "list of elements with qualified name qualifiedName", `createElement()` `createAttribute()`, and other attr stuff, where we can pass not only Ascii characters Using this definitiona doesn't suggest that conversion is making only for Ascii characters? 

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Reply to this email directly or view it on GitHub:
https://github.com/whatwg/dom/issues/159