msglist [nfc]: Place _allMessagesVisible right after _messageVisible

This is solely for a better order.

Author: sm-sayedi

lib/model/message_list.dart

@@ -448,39 +448,39 @@ class MessageListView with ChangeNotifier, _MessageSequence {
     }
   }
 
-  /// Whether this event could affect the result that [_messageVisible]
-  /// would ever have returned for any possible message in this message list.
-  VisibilityEffect _canAffectVisibility(UserTopicEvent event) {
+  /// Whether [_messageVisible] is true for all possible messages.
+  ///
+  /// This is useful for an optimization.
+  bool get _allMessagesVisible {
     switch (narrow) {
       case CombinedFeedNarrow():
-        return store.willChangeIfTopicVisible(event);
-
-      case ChannelNarrow(:final streamId):
-        if (event.streamId != streamId) return VisibilityEffect.none;
-        return store.willChangeIfTopicVisibleInStream(event);
+      case ChannelNarrow():
+        return false;
 
       case TopicNarrow():
       case DmNarrow():
       case MentionsNarrow():
       case StarredMessagesNarrow():
-        return VisibilityEffect.none;
+        return true;
     }
   }
 
-  /// Whether [_messageVisible] is true for all possible messages.
-  ///
-  /// This is useful for an optimization.
-  bool get _allMessagesVisible {
+  /// Whether this event could affect the result that [_messageVisible]
+  /// would ever have returned for any possible message in this message list.
+  VisibilityEffect _canAffectVisibility(UserTopicEvent event) {
     switch (narrow) {
       case CombinedFeedNarrow():
-      case ChannelNarrow():
-        return false;
+        return store.willChangeIfTopicVisible(event);
+
+      case ChannelNarrow(:final streamId):
+        if (event.streamId != streamId) return VisibilityEffect.none;
+        return store.willChangeIfTopicVisibleInStream(event);
 
       case TopicNarrow():
       case DmNarrow():
       case MentionsNarrow():
       case StarredMessagesNarrow():
-        return true;
+        return VisibilityEffect.none;
     }
   }