Sort out what's happening with innerHTML on <script> and <style> in XML documents

In at least Chrome, Safari, and Firefox, it looks like this:

var style = document.createElementNS("http://www.w3.org/1999/xhtml", "style");
style.innerHTML = "<foo></foo>";

will create a textnode with the text "<foo></foo>" as a child of the <style> element. Even if this is happening in an XML/XHTML document.

Per spec, I would think in an XML document this should create a child element named "foo", no?

I haven't had a chance to check what IE/Edge do here yet. /cc @annevk @smaug----

Start by checking the reported innerHTML behavior for style elements created with createElementNS in XML/XHTML documents across the cited browsers. Compare those results with the applicable DOM Parsing and XML/HTML specifications, including the expected handling of the foo element. Done means the normative behavior and any required specification change are clearly determined.