Use amp-nested-menu to implement mobile menu in Twenty Nineteen

[westonruter]

Feature description

When AMP compatibility was added for the Twenty Nineteen theme, we tried our best to implement support for the mobile menu (or rather, to use CSS only to implement the feature: WordPress/twentynineteen#337):

However, we weren't able to implement this without JS (see touch-keyboard-navigation.js), so we had to ship the no-JS fallback experience for AMP (#1587).

However, there is now an AMP component dedicated for this purpose: amp-nested-menu. We should now leverage it in the core theme sanitizer.

---

Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance criteria

Implementation brief

QA testing instructions

Demo

Changelog entry

[westonruter]

Marking this as P1 since we'll be using Twenty Nineteen potentially as one of the templates we make available in Reader mode.

[westonruter]

The Bento version of amp-sidebar is incompatible with non-Bento amp-nested-menu. Since there is no Bento version of amp-nested-menu yet, this issue is blocked.

[pavanpatil1]

QA Passed ✅

Cross-checked the issue, Fix is working as expected.

Non AMP

navnonamp.mp4

AMP

navamp.mp4