remove unnecessary overrides (#23650)

dev/integration_tests/channels/lib/main.dart

@@ -156,11 +156,6 @@ class _TestAppState extends State<TestApp> {
   Future<TestStepResult> _result;
   int _step = 0;
 
-  @override
-  void initState() {
-    super.initState();
-  }
-
   void _executeNextStep() {
     setState(() {
       if (_step < steps.length)

dev/integration_tests/platform_interaction/lib/main.dart

@@ -27,11 +27,6 @@ class _TestAppState extends State<TestApp> {
   Future<TestStepResult> _result;
   int _step = 0;
 
-  @override
-  void initState() {
-    super.initState();
-  }
-
   void _executeNextStep() {
     setState(() {
       if (_step < steps.length)

packages/flutter/test/painting/decoration_test.dart

@@ -61,11 +61,6 @@ class DelayedImageProvider extends ImageProvider<DelayedImageProvider> {
     return SynchronousFuture<DelayedImageProvider>(this);
   }
 
-  @override
-  ImageStream resolve(ImageConfiguration configuration) {
-    return super.resolve(configuration);
-  }
-
   @override
   ImageStreamCompleter load(DelayedImageProvider key) {
     return OneFrameImageStreamCompleter(_completer.future);