Add autofill support for TextFormField (#57332)

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

@@ -174,6 +174,7 @@ class TextFormField extends FormField<String> {
     bool enableInteractiveSelection = true,
     InputCounterWidgetBuilder buildCounter,
     ScrollPhysics scrollPhysics,
+    Iterable<String> autofillHints,
   }) : assert(initialValue == null || controller == null),
        assert(textAlign != null),
        assert(autofocus != null),
@@ -257,6 +258,7 @@ class TextFormField extends FormField<String> {
         keyboardAppearance: keyboardAppearance,
         enableInteractiveSelection: enableInteractiveSelection,
         buildCounter: buildCounter,
+        autofillHints: autofillHints,
       );
     },
   );

packages/flutter/test/material/text_form_field_test.dart

@@ -425,4 +425,21 @@ void main() {
     expect(find.text('initialValue'), findsNothing);
     expect(find.text('changedValue'), findsOneWidget);
   });
+
+  testWidgets('autofillHints is passed to super', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Material(
+          child: Center(
+            child: TextFormField(
+              autofillHints: const <String>[AutofillHints.countryName],
+            ),
+          ),
+        ),
+      ),
+    );
+
+    final TextField widget = tester.widget(find.byType(TextField));
+    expect(widget.autofillHints, equals(const <String>[AutofillHints.countryName]));
+  });
 }