Eliminate static emoji handling since most browsers now support natively

[westonruter]

Summary

I've been doing some looking into emoji handling in WordPress, as I've realized that I'm not seeing Twemoji images for emoji anymore. From caniemoji.com it seems all modern platforms/browsers now natively support native emoji, so the emoji detection script and dns-prefetch for s.w.org is largely just slowing down page performance in WordPress.

For more in core:

• https://core.trac.wordpress.org/ticket/37788#comment:4
• https://core.trac.wordpress.org/ticket/35498#comment:7
• https://core.trac.wordpress.org/ticket/41405#comment:5

We can improve performance of pages prepared by the AMP plugin by skipping the wp_staticize_emoji() calls (which were neither comprehensive to the whole page nor largely necessary given native browser support), eliminating any connections to WordPress's Twemoji CDN at s.w.org.

Another benefit to eliminating the use of wp_staticize_emoji() is that it outputs not SVG but PNG images (by default), meaning they have appeared quite poor at larger font sizes.

Before	After

Checklist

• My code is tested and passes existing tests.
• My code follows the Engineering Guidelines (updates are often made to the guidelines, check it out periodically).

[github-actions]

Plugin builds for 7244902 are ready 🛎️!

• Download development build
• Download production build

[dhaval-parekh]

Changes in PR looks good to me 👍

---

I have tested the changes in different browsers and the results are consistent across the browsers.

Browser	Preview
Firefox
Chrome
Safari
Microsoft Edge

[bartoszgadomski]

QA passed:

Browser	non-AMP	AMP
Chrome
Firefox
Safari

Also, connections to s.w.org are eliminated.
Well done 👍