Rename JSX files with proper .jsx extension (#23733)

app/javascript/mastodon/components/icon_with_badge.jsx

@@ -0,0 +1,22 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import Icon from 'mastodon/components/icon';
+
+const formatNumber = num => num > 40 ? '40+' : num;
+
+const IconWithBadge = ({ id, count, issueBadge, className }) => (
+  <i className='icon-with-badge'>
+    <Icon id={id} fixedWidth className={className} />
+    {count > 0 && <i className='icon-with-badge__badge'>{formatNumber(count)}</i>}
+    {issueBadge && <i className='icon-with-badge__issue-badge' />}
+  </i>
+);
+
+IconWithBadge.propTypes = {
+  id: PropTypes.string.isRequired,
+  count: PropTypes.number.isRequired,
+  issueBadge: PropTypes.bool,
+  className: PropTypes.string,
+};
+
+export default IconWithBadge;