"Review type" field is never enabled if you use keyboard only

On edge, the "Review type" field is now below the comment box, and is theoretically only enabled if you elect to do a review. By default, a comment is only a comment and is not allowed to have a review type.

Steps to reproduce:
  * Find a code review
  * Type some stuff in the comment field
  * Hit "Tab"
  * Select "Approve" with the keyboard (i.e. hit the down arrow)
  * Hit "Tab"

What I expect:
  * The cursor to appear in the "Review type" input field, ready for me to enter a review type

What I see:
  * The "Save comment" button activated, the "Review type" input field disabled.

This bug exists on production, but it's much less obvious, probably since the "Review" pulldown box cannot be conveniently reached via keyboard navigation.