Focus disappears if modal transitions to new page

[toolness]

Right now our focus logic assumes modals will transfer focus back to where it was before the modal opened, but this focus doesn't exist when the modal is transferring the user to a new page (e.g. the penultimate step of onboarding), which results in an undefined focus.

[toolness]

Hmm, this does still seem to be an issue. I just verified it by visiting http://localhost:8000/en/onboarding/step/3 and choosing an option that opened an interstitial modal, and when I confirm the modal, there's no focus.

I also made the focus super-visible by modifying the CSS a bit:

 // the element, so we'll do that here. For more details, see:
 // https://css-tricks.com/focus-styles-non-interactive-elements/
 [data-jf-is-noninteractive]:focus {
-  outline: none;
+  outline: 5px solid blue;
 }