Emoji: Upgrade Twemoji to 12.1.2.

This upgrade adds support for the transgender flag: 🏳️‍⚧️

There's some additional housekeeping in this commit:

- Twemoji recently rearranged their repository and package, so `Gruntfile.js` needed tweaking to allow for that.
- As only new files were added in this Twemoji release, the CDN version didn't need updating.

Fixes #47852.



git-svn-id: https://develop.svn.wordpress.org/trunk@45769 602fd350-edb4-49c9-b593-d223f7449a82

src/js/_enqueues/lib/emoji-loader.js

@@ -68,6 +68,22 @@
 
 		switch ( type ) {
 			case 'flag':
+				/*
+				 * Test for Transgender flag compatibility. This flag is shortlisted for the Emoji 13 spec,
+				 * but has landed in Twemoji early, so we can add support for it, too.
+				 *
+				 * To test for support, we try to render it, and compare the rendering to how it would look if
+				 * the browser doesn't render it correctly (white flag emoji + transgender symbol).
+				 */
+				isIdentical = emojiSetsRenderIdentically(
+					[ 0x1F3F3, 0xFE0F, 0x200D, 0x26A7, 0xFE0F ],
+					[ 0x1F3F3, 0xFE0F, 0x200B, 0x26A7, 0xFE0F ]
+				);
+
+				if ( isIdentical ) {
+					return false;
+				}
+
 				/*
 				 * Test for UN flag compatibility. This is the least supported of the letter locale flags,
 				 * so gives us an easy test for full support.