update MDN links in reusable modules tutorial
Merge pull request #1312 from groovecoder/mdn-links-reusable-modules-tutorial

update MDN links in reusable modules tutorial
Extend functional utils
Merge pull request #1313 from Gozala/bug/functional@854982

Bug 854982 - Extend functional utils. r=@jsantell
Fix docs that got broken by pull request #1313 a=@gozala