Missing integration with new unsafe HTML parsing methods

[lukewarlow]

See https://html.spec.whatwg.org/multipage/dynamic-markup-insertion.html#unsafe-html-parsing-methods

Currently they are:

partial interface Element {
  [CEReactions] undefined setHTMLUnsafe(DOMString html);
};

partial interface ShadowRoot {
  [CEReactions] undefined setHTMLUnsafe(DOMString html);
};

They should be:

partial interface Element {
  [CEReactions] undefined setHTMLUnsafe(HTMLString html);
};

partial interface ShadowRoot {
  [CEReactions] undefined setHTMLUnsafe(HTMLString html);
};

[lukewarlow]

Potentially also need to update parseHTMLUnsafe it's unclear to me if this actually executes anything there also appears to be a bug in the spec where the IDL for it is missing