Fix typo (#42922)

packages/flutter/lib/src/material/tab_controller.dart

@@ -11,7 +11,7 @@ import 'constants.dart';
 /// Coordinates tab selection between a [TabBar] and a [TabBarView].
 ///
 /// The [index] property is the index of the selected tab and the [animation]
-/// represents the current scroll positions of the tab bar and the tar bar view.
+/// represents the current scroll positions of the tab bar and the tab bar view.
 /// The selected tab's index can be changed with [animateTo].
 ///
 /// A stateful widget that builds a [TabBar] or a [TabBarView] can create