Revert "Change links in webUI to rewrite misleading links (#11426)" (#11500)

This reverts commit b31b232edf.

app/javascript/mastodon/utils/idna.js

@@ -1,10 +0,0 @@
-import punycode from 'punycode';
-
-const IDNA_PREFIX = 'xn--';
-
-export const decode = domain => {
-  return domain
-    .split('.')
-    .map(part => part.indexOf(IDNA_PREFIX) === 0 ? punycode.decode(part.slice(IDNA_PREFIX.length)) : part)
-    .join('.');
-};