Possibly missing lowercasing step for `autocomplete` attribute

[devgianlu]

What is the issue with the HTML Standard?

While implementing support for the autocomplete attribute on form associated elements I stumbled upon a possible issue: the WPT tests assume that the field value will be transformed to be lowercase, but I could not see where it is explictly stated. All I can see is that the comparisons should be case insensitive. It seems to work fine if at step 15 I also perform lowercasing.

Spec: https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#autofill-processing-model
WPT test: https://github.com/web-platform-tests/wpt/blob/master/html/semantics/forms/the-form-element/form-autocomplete.html
Implementation PR: LadybirdBrowser/ladybird#3517

[annevk]

Yeah, that seems like a bug.

cc @whatwg/forms