fix gif autoplay on iOS (#21422)

app/javascript/mastodon/components/media_gallery.js

@@ -4,7 +4,6 @@ import PropTypes from 'prop-types';
 import { is } from 'immutable';
 import IconButton from './icon_button';
 import { defineMessages, injectIntl, FormattedMessage } from 'react-intl';
-import { isIOS } from '../is_mobile';
 import classNames from 'classnames';
 import { autoPlayGif, cropImages, displayMedia, useBlurhash } from '../initial_state';
 import { debounce } from 'lodash';
@@ -181,7 +180,7 @@ class Item extends React.PureComponent {
         </a>
       );
     } else if (attachment.get('type') === 'gifv') {
-      const autoPlay = !isIOS() && this.getAutoPlay();
+      const autoPlay = this.getAutoPlay();
 
       thumbnail = (
         <div className={classNames('media-gallery__gifv', { autoplay: autoPlay })}>
@@ -195,6 +194,7 @@ class Item extends React.PureComponent {
             onMouseEnter={this.handleMouseEnter}
             onMouseLeave={this.handleMouseLeave}
             autoPlay={autoPlay}
+            playsInline
             loop
             muted
           />