Keyboard Shortcut dialog on Help page is broken

Summary

The keyboard shortcuts dialog does not open.

Note this also effects the ? shortcut though that doesn't seem to produce an error.

Steps to reproduce

Go to https://gitlab.com/help and click "Use shortcuts" in the right sidebar. No dialog will appear.

What is the current bug behavior?

A JS error occurs.

What is the expected correct behavior?

The shortcut dialog should show up and show me all the available keyboard shortcuts.

Relevant logs and/or screenshots

Uncaught ReferenceError: Shortcuts is not defined
    at HTMLAnchorElement.onclick (help:294)

Output of checks

This bug happens on GitLab.com, v10.2.4. Reproduced on CE 10.2.4 as well.