Add accessibility text-transform test for full-size-kana

[cookiecrook]

Since implementors seem to be in agreement that text-transform: full-size-kana should not affect accessibility text in the API, we should add a computedlabel test to verify that. It should be .tentative at first since I think none of the implementations will pass the test initially.

Related:

• [css-text-3] text-transform: full-size-kana w3c/csswg-drafts#3143
• https://webkit.org/b/261565

[adampage]

I’ve got a great test case for this. びょういん (hospital) versus びよういん (beauty parlor).

A person’s life could literally depend on the faithful exposure of the non-full-size-kana form. 😅