mdn: adapt for yari

[myfreeer]

Recently, mdn has switched its backend to yari, which has changed a lot of its behavior.

Below is an incomplete list of changes:

• Pages not available in current locale but available in english would result in 404 (#196)
• Browser compatibility table is rendered in browser side, via ajax, instead of server-side. (#194)
• Some links are replaced with ajax and in-place render, but following the link would still work. (commit 47204804)
• Sitemaps are likely to be gzipped. (#214)
• Scripts are packed with webpack and is likely to have runtime-loaded script chunks. (Sign-in modal) (commit 47204804)
• Links in header bar is nolonger localized.
• Many redirects are missing and many archived contents were gone. (Even if they are in search results)
• Many translated redirects are missing, but the content is still there with the sitemap as the only entrance. (translation_of and translation_of_original not parsed)
• Style of old compatibility table is gone. (commit 8f454067)

To adapt for that, we might need to:

• Manually fallback to en-US in case of 404. (#196)
• Drop all the scripts or mock fetch api with a more complete response list, or drop all the scripts and manually implement the ui actions with js or css. (#193) (#534)
• Get the browser compatibility table and render it to page manually or mock the api. (#194) (#629) (#630)
• Prevent attaching events to links or stopImmediatePropagation before SPA rendering invoked.
• Inject back the style of old compatibility table (commit 8f454067)

[myfreeer]

Browser compatibility table seems complex for rendering. Link: #194

[myfreeer]

Main page is not localized now