msglist [nfc]: moved valueListenable to keep builder and child together in ScrollToBottomButton

Author: sirpengi

lib/widgets/message_list.dart

@@ -251,10 +251,10 @@ class ScrollToBottomButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return ValueListenableBuilder<bool>(
+      valueListenable: visibleValue,
       builder: (BuildContext context, bool value, Widget? child) {
         return (value && child != null) ? child : const SizedBox.shrink();
       },
-      valueListenable: visibleValue,
       // TODO: fix hardcoded values for size and style here
       child: IconButton(
         tooltip: "Scroll to bottom",