Fix minor typos in comments and spec names (#21831)

app/javascript/mastodon/utils/__tests__/html-test.js

@@ -1,7 +1,7 @@
 import * as html from '../html';
 
 describe('html', () => {
-  describe('unsecapeHTML', () => {
+  describe('unescapeHTML', () => {
     it('returns unescaped HTML', () => {
       const output = html.unescapeHTML('<p>lorem</p><p>ipsum</p><br>&lt;br&gt;');
       expect(output).toEqual('lorem\n\nipsum\n<br>');