Revert bug 893276 due to permanent failures.

This reverts commit 4f3ef6ced9a1377afd7c3dc3bf232c0183fd47c6, reversing
changes made to 7b5f80a40e79506293c58ba1c337c93be45423b2.
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
Bug 922558: Add contextMenu.PredicateContext. r=Mossop