css/selectors/case-insensitive-parent.html is wrong

[annevk]

https://github.com/web-platform-tests/wpt/blob/master/css/selectors/case-insensitive-parent.html is wrong per https://html.spec.whatwg.org/#case-sensitivity-of-selectors. Only HTML elements inside HTML documents get matched ASCII case-insensitively.

[noamr]

@lilles

seems like this landed as part of a chromium commit (https://chromium-review.git.corp.google.com/c/chromium/src/+/4286739) and I believe the test asserts the wrong thing.