Caption buttons are no longer tab focusable

[bsclifton]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Fixes #4846

Auditors: @bbondy

Test plan:

1. Launch Brave on Windows and set focus to URL bar
2. Press tab to move focus and hit enter
3. Window should not minimize, maximize, or close (focus should have went
   to the page)

[bbondy]

object destructuring ftw