msglist [nfc]: Reorder methods to group mutators together

This messageContentChanged method goes logically next to the
various event-handling methods, rather than separated from them
by notifyListeners and its siblings.

Author: gnprice

lib/model/message_list.dart

@@ -474,6 +474,17 @@ class MessageListView with ChangeNotifier, _MessageSequence {
     notifyListeners();
   }
 
+  /// Update data derived from the content of the given message.
+  ///
+  /// This does not notify listeners.
+  /// The caller should ensure that happens later.
+  void messageContentChanged(int messageId) {
+    final index = _findMessageWithId(messageId);
+    if (index != -1) {
+      _reparseContent(index);
+    }
+  }
+
   // Repeal the `@protected` annotation that applies on the base implementation,
   // so we can call this method from [MessageStoreImpl].
   @override
@@ -497,17 +508,6 @@ class MessageListView with ChangeNotifier, _MessageSequence {
     }
   }
 
-  /// Update data derived from the content of the given message.
-  ///
-  /// This does not notify listeners.
-  /// The caller should ensure that happens later.
-  void messageContentChanged(int messageId) {
-    final index = _findMessageWithId(messageId);
-    if (index != -1) {
-      _reparseContent(index);
-    }
-  }
-
   /// Called when the app is reassembled during debugging, e.g. for hot reload.
   ///
   /// This will redo from scratch any computations we can, such as parsing