Make printing workboards work OK

Summary:
Fixes T7844. This isn't going to win any awards, but it has all the information.

Mostly, we don't (or shouldn't, at least?) need the global static stuff anymore because we dropped the top-level custom scrollbar.

Test Plan: Printed a PDF of a workboard, got all the cards in the output.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T7844

Differential Revision: https://secure.phabricator.com/D15205