Fix TextEditingController doc to call super.initState first (#51089)

packages/flutter/lib/src/widgets/editable_text.dart

diff --git a/packages/flutter/lib/src/widgets/editable_text.dart b/packages/flutter/lib/src/widgets/editable_text.dart
index 880527d..4847b4b 100644
--- a/packages/flutter/lib/src/widgets/editable_text.dart
+++ b/packages/flutter/lib/src/widgets/editable_text.dart
@@ -79,6 +79,7 @@
 /// final _controller = TextEditingController();
 ///
 /// void initState() {
+///   super.initState();
 ///   _controller.addListener(() {
 ///     final text = _controller.text.toLowerCase();
 ///     _controller.value = _controller.value.copyWith(
@@ -87,7 +88,6 @@
 ///       composing: TextRange.empty,
 ///     );
 ///   });
-///   super.initState();
 /// }
 ///
 /// void dispose() {