cache matched defaults sets for given parameters (#6888)
cache matched defaults sets for given parameters (#6888)

Merge pull request 6888
jekyll/jekyll,tillgrallert/jekyll,chrisfinazzo/jekyll,x-way/jekyll,jaybe-jekyll/jekyll,ryanshaw/jekyll,fulldecent/jekyll,chrisfinazzo/jekyll,Strangehill/jekyll,Strangehill/jekyll,tillgrallert/jekyll,x-way/jekyll,jaybe-jekyll/jekyll,jaybe-jekyll/jekyll,ryanshaw/jekyll,jekyll/jekyll,jekyll/jekyll,fulldecent/jekyll,tillgrallert/jekyll,chrisfinazzo/jekyll,chrisfinazzo/jekyll,fulldecent/jekyll,x-way/jekyll,yhironaka/yhironaka.github.io,ryanshaw/jekyll,tillgrallert/jekyll,x-way/jekyll,tillgrallert/jekyll,ryanshaw/jekyll,Strangehill/jekyll,jekyll/jekyll,fulldecent/jekyll,Strangehill/jekyll,jaybe-jekyll/jekyll,Strangehill/jekyll