[Transition experiment] Follow up the latest spec of API

[yhatt]

• Following up the latest spec of API
  • setElement has removed from JavaScript API. WICG/view-transitions@0f7e52a

• Make resilience from API error
  • If there were duplicated page-transition-tag by the custom CSS, the slide had been not navigatable by failure of DocumentTransition.prototype.start. When caught an error while running page.start(), we will fallback to the regular navigation.

• Update the base style for transition with shared elements.
  • General cross-fading animation is set also to transition tags declared by users. It allows transition with the shared elements, just like PowerPoint's Morph and Keynote's Magic Move!

---
marp: true
theme: gaia
_class: lead
transition: slide 1s
style: |
  section > h1:first-of-type {
    contain: paint;
    page-transition-tag: title;
  }
  img[alt~="shared"] {
    contain: paint;
    page-transition-tag: image;
  }
---

![shared w:400](https://marp.app/assets/marp.svg)

# Transition with shared element

---

# It's a Magic! 🪄

![shared w:500](https://media1.giphy.com/media/ujUdrdpX7Ok5W/giphy.gif)