[dom] Pull Request: Run the adopting steps recursively

nox has just submitted a new pull request for 
https://github.com/whatwg/dom:

== Run the adopting steps recursively ==
When adopting a <template>'s template contents and running its own 
adopting steps as defined in HTML, if the adopting steps aren't 
recursively, any nested template won't see its template contents' 
owner document changed.

See https://github.com/whatwg/dom/pull/66