Merge commit 'f79b96a5ef0f6c4f57eee7f44ce2579b28a22098' into glitch-soc/merge-upstream

Conflicts:
- `app/lib/feed_manager.rb`:
  Not a real conflict, but glitch-soc has an extra `populate_direct_feed` method.
  Added upstream's code.
- `app/models/user_settings.rb`:
  Not a real conflict, glitch-soc has an extra setting textually-adjacent to a
  setting added upstream.
  Added upstream's setting.
- `app/serializers/initial_state_serializer.rb`:
  Same.
- `app/services/precompute_feed_service.rb`:
  Not a real conflict, glitch-soc has extra code for the direct feed.
  Added upstream's new code for populating lists.

app/javascript/mastodon/features/compose/components/compose_form.jsx

@@ -10,6 +10,8 @@ import ImmutablePureComponent from 'react-immutable-pure-component';
 
 import { length } from 'stringz';
 
+import { missingAltTextModal } from 'mastodon/initial_state';
+
 import AutosuggestInput from '../../../components/autosuggest_input';
 import AutosuggestTextarea from '../../../components/autosuggest_textarea';
 import { Button } from '../../../components/button';
@@ -65,6 +67,7 @@ class ComposeForm extends ImmutablePureComponent {
     autoFocus: PropTypes.bool,
     withoutNavigation: PropTypes.bool,
     anyMedia: PropTypes.bool,
+    missingAltText: PropTypes.bool,
     isInReply: PropTypes.bool,
     singleColumn: PropTypes.bool,
     lang: PropTypes.string,
@@ -117,7 +120,7 @@ class ComposeForm extends ImmutablePureComponent {
       return;
     }
 
-    this.props.onSubmit();
+    this.props.onSubmit(missingAltTextModal && this.props.missingAltText);
 
     if (e) {
       e.preventDefault();