Docs version picker makes sidenav hard to use with a keyboard or screen reader

[marcysutton]

Actual Behavior:

• What is the issue? *
  Version picker links in the docs sidenav aren't hidden from keyboard and screen reader users when the list is visually closed. That means it's still a huge pain to try to navigate the sidebar with a keyboard. This issue was open previously as Angular Material site sidenav: hidden nav items should not be reachable from the keyboard #4106, and it still exists.
• What is the expected behavior?
  The menu-toggle-list should be hidden with display: none after animating completes. This could be done with CSS keyframes if it impacts the animation. Alternatively, links could be removed from the tab order with tabindex="-1" on each control and aria-hidden="true" on the parent, but that would take more work.

CodePen (or steps to reproduce the issue): *

• CodePen Demo which shows your issue:
• Details:
  Go to any page on https://material.angularjs.org and try to tab through the sidenav. Observe your keyboard focus go through every item in the (closed) version picker, and then the expand/collapse links which work correctly.

See the version picker announced even when it is closed:

Angular Versions: *

• Angular Version:
• Angular Material Version:
  Current / All past versions

Additional Information:

• Browser Type: *
• Browser Version: *
• OS: *
• Stack Traces:
  All - Visible with keyboard alone, but also with Voiceover, NVDA, JAWS, etc.

---

Shortcut to create a new CodePen Demo.
Note: * indicates required information. Without this information, your issue may be auto-closed.

Do not modify the titles or questions. Simply add your responses to the ends of the questions.
Add more lines if needed.

[marcysutton]

Yay!