Ensure tabIndex is number instead of string (#24409)

app/javascript/mastodon/components/dropdown_menu.jsx

@@ -119,7 +119,7 @@ class DropdownMenu extends React.PureComponent {
 
     return (
       <li className='dropdown-menu__item' key={`${text}-${i}`}>
-        <a href={href} target={target} data-method={method} rel='noopener noreferrer' role='button' tabIndex='0' ref={i === 0 ? this.setFocusRef : null} onClick={this.handleClick} onKeyPress={this.handleItemKeyPress} data-index={i}>
+        <a href={href} target={target} data-method={method} rel='noopener noreferrer' role='button' tabIndex={0} ref={i === 0 ? this.setFocusRef : null} onClick={this.handleClick} onKeyPress={this.handleItemKeyPress} data-index={i}>
           {text}
         </a>
       </li>