Reduce allocations from Jekyll::Document instances (#7625)
Reduce allocations from Jekyll::Document instances (#7625)

Merge pull request 7625
x-way/jekyll,chrisfinazzo/jekyll,Strangehill/jekyll,tillgrallert/jekyll,chrisfinazzo/jekyll,jaybe-jekyll/jekyll,chrisfinazzo/jekyll,fulldecent/jekyll,jaybe-jekyll/jekyll,Strangehill/jekyll,fulldecent/jekyll,jaybe-jekyll/jekyll,ryanshaw/jekyll,tillgrallert/jekyll,chrisfinazzo/jekyll,fulldecent/jekyll,x-way/jekyll,fulldecent/jekyll,tillgrallert/jekyll,ryanshaw/jekyll,x-way/jekyll,jekyll/jekyll,ryanshaw/jekyll,Strangehill/jekyll,ryanshaw/jekyll,Strangehill/jekyll,tillgrallert/jekyll,yhironaka/yhironaka.github.io,Strangehill/jekyll,jekyll/jekyll,jekyll/jekyll,x-way/jekyll,jekyll/jekyll,tillgrallert/jekyll,jaybe-jekyll/jekyll