make immutables const (#32340)

* make immutables const

examples/flutter_gallery/lib/demo/contacts_demo.dart

@@ -42,7 +42,7 @@ class _ContactCategory extends StatelessWidget {
 }
 
 class _ContactItem extends StatelessWidget {
-  _ContactItem({ Key key, this.icon, this.lines, this.tooltip, this.onPressed })
+  const _ContactItem({ Key key, this.icon, this.lines, this.tooltip, this.onPressed })
     : assert(lines.length > 1),
       super(key: key);
 

packages/flutter/lib/src/cupertino/bottom_tab_bar.dart

@@ -37,7 +37,7 @@ const Color _kDefaultTabBarBorderColor = Color(0x4C000000);
 ///  * [BottomNavigationBarItem], an item in a [CupertinoTabBar].
 class CupertinoTabBar extends StatelessWidget implements PreferredSizeWidget {
   /// Creates a tab bar in the iOS style.
-  CupertinoTabBar({
+  const CupertinoTabBar({
     Key key,
     @required this.items,
     this.onTap,

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

@@ -132,7 +132,7 @@ class Stepper extends StatefulWidget {
   /// new one.
   ///
   /// The [steps], [type], and [currentStep] arguments must not be null.
-  Stepper({
+  const Stepper({
     Key key,
     @required this.steps,
     this.physics,

packages/flutter/test/widgets/clip_test.dart

@@ -41,7 +41,7 @@ class ValueClipper<T> extends CustomClipper<T> {
 }
 
 class _UpdateCountedClipRect extends ClipRect {
-  _UpdateCountedClipRect({Clip clipBehavior = Clip.antiAlias})
+  const _UpdateCountedClipRect({Clip clipBehavior = Clip.antiAlias})
     : super(clipBehavior: clipBehavior);
 }
 
@@ -51,24 +51,24 @@ class _UpdateCountedClipRRect extends ClipRRect {
 }
 
 class _UpdateCountedClipOval extends ClipOval {
-  _UpdateCountedClipOval({Clip clipBehavior = Clip.antiAlias})
+  const _UpdateCountedClipOval({Clip clipBehavior = Clip.antiAlias})
       : super(clipBehavior: clipBehavior);
 }
 
 class _UpdateCountedClipPath extends ClipPath {
-  _UpdateCountedClipPath({Clip clipBehavior = Clip.antiAlias})
+  const _UpdateCountedClipPath({Clip clipBehavior = Clip.antiAlias})
       : super(clipBehavior: clipBehavior);
 }
 
 void main() {
   testWidgets('ClipRect updates clipBehavior in updateRenderObject', (WidgetTester tester) async {
-    await tester.pumpWidget(_UpdateCountedClipRect());
+    await tester.pumpWidget(const _UpdateCountedClipRect());
 
     final RenderClipRect renderClip = tester.allRenderObjects.whereType<RenderClipRect>().first;
 
     expect(renderClip.clipBehavior, equals(Clip.antiAlias));
 
-    await tester.pumpWidget(_UpdateCountedClipRect(clipBehavior: Clip.hardEdge));
+    await tester.pumpWidget(const _UpdateCountedClipRect(clipBehavior: Clip.hardEdge));
 
     expect(renderClip.clipBehavior, equals(Clip.hardEdge));
   });
@@ -86,25 +86,25 @@ void main() {
   });
 
   testWidgets('ClipOval updates clipBehavior in updateRenderObject', (WidgetTester tester) async {
-    await tester.pumpWidget(_UpdateCountedClipOval());
+    await tester.pumpWidget(const _UpdateCountedClipOval());
 
     final RenderClipOval renderClip = tester.allRenderObjects.whereType<RenderClipOval>().first;
 
     expect(renderClip.clipBehavior, equals(Clip.antiAlias));
 
-    await tester.pumpWidget(_UpdateCountedClipOval(clipBehavior: Clip.hardEdge));
+    await tester.pumpWidget(const _UpdateCountedClipOval(clipBehavior: Clip.hardEdge));
 
     expect(renderClip.clipBehavior, equals(Clip.hardEdge));
   });
 
   testWidgets('ClipPath updates clipBehavior in updateRenderObject', (WidgetTester tester) async {
-    await tester.pumpWidget(_UpdateCountedClipPath());
+    await tester.pumpWidget(const _UpdateCountedClipPath());
 
     final RenderClipPath renderClip = tester.allRenderObjects.whereType<RenderClipPath>().first;
 
     expect(renderClip.clipBehavior, equals(Clip.antiAlias));
 
-    await tester.pumpWidget(_UpdateCountedClipPath(clipBehavior: Clip.hardEdge));
+    await tester.pumpWidget(const _UpdateCountedClipPath(clipBehavior: Clip.hardEdge));
 
     expect(renderClip.clipBehavior, equals(Clip.hardEdge));
   });

packages/flutter/test/widgets/physical_model_test.dart

@@ -11,19 +11,19 @@ import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 class _UpdateCountedPhysicalModel extends PhysicalModel {
-  _UpdateCountedPhysicalModel({Clip clipBehavior = Clip.none})
+  const _UpdateCountedPhysicalModel({Clip clipBehavior = Clip.none})
     : super(clipBehavior: clipBehavior, color: Colors.red);
 }
 
 class _UpdateCountedPhysicalShape extends PhysicalShape {
-  _UpdateCountedPhysicalShape({Clip clipBehavior = Clip.none})
+  const _UpdateCountedPhysicalShape({Clip clipBehavior = Clip.none})
       : super(clipBehavior: clipBehavior, color: Colors.red, clipper: const ShapeBorderClipper(shape: CircleBorder()));
 }
 
 void main() {
   testWidgets('PhysicalModel updates clipBehavior in updateRenderObject', (WidgetTester tester) async {
     await tester.pumpWidget(
-      MaterialApp(home: _UpdateCountedPhysicalModel()),
+      const MaterialApp(home: _UpdateCountedPhysicalModel()),
     );
 
     final RenderPhysicalModel renderPhysicalModel = tester.allRenderObjects.whereType<RenderPhysicalModel>().first;
@@ -31,7 +31,7 @@ void main() {
     expect(renderPhysicalModel.clipBehavior, equals(Clip.none));
 
     await tester.pumpWidget(
-      MaterialApp(home: _UpdateCountedPhysicalModel(clipBehavior: Clip.antiAlias)),
+      const MaterialApp(home: _UpdateCountedPhysicalModel(clipBehavior: Clip.antiAlias)),
     );
 
     expect(renderPhysicalModel.clipBehavior, equals(Clip.antiAlias));
@@ -39,7 +39,7 @@ void main() {
 
   testWidgets('PhysicalShape updates clipBehavior in updateRenderObject', (WidgetTester tester) async {
     await tester.pumpWidget(
-      MaterialApp(home: _UpdateCountedPhysicalShape()),
+      const MaterialApp(home: _UpdateCountedPhysicalShape()),
     );
 
     final RenderPhysicalShape renderPhysicalShape = tester.allRenderObjects.whereType<RenderPhysicalShape>().first;
@@ -47,7 +47,7 @@ void main() {
     expect(renderPhysicalShape.clipBehavior, equals(Clip.none));
 
     await tester.pumpWidget(
-      MaterialApp(home: _UpdateCountedPhysicalShape(clipBehavior: Clip.antiAlias)),
+      const MaterialApp(home: _UpdateCountedPhysicalShape(clipBehavior: Clip.antiAlias)),
     );
 
     expect(renderPhysicalShape.clipBehavior, equals(Clip.antiAlias));

packages/flutter/test/widgets/slivers_keepalive_test.dart

@@ -9,9 +9,9 @@ import 'package:flutter/rendering.dart';
 void main() {
   testWidgets('Sliver with keep alive without key - should dispose after reodering', (WidgetTester tester) async {
     List<Widget> childList= <Widget>[
-      WidgetTest0(text: 'child 0', keepAlive: true),
-      WidgetTest1(text: 'child 1', keepAlive: true),
-      WidgetTest2(text: 'child 2', keepAlive: true),
+      const WidgetTest0(text: 'child 0', keepAlive: true),
+      const WidgetTest1(text: 'child 1', keepAlive: true),
+      const WidgetTest2(text: 'child 2', keepAlive: true),
     ];
     await tester.pumpWidget(SwitchingChildListTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -32,9 +32,9 @@ void main() {
 
   testWidgets('Sliver without keep alive without key - should dispose after reodering', (WidgetTester tester) async {
     List<Widget> childList= <Widget>[
-      WidgetTest0(text: 'child 0'),
-      WidgetTest1(text: 'child 1'),
-      WidgetTest2(text: 'child 2'),
+      const WidgetTest0(text: 'child 0'),
+      const WidgetTest1(text: 'child 1'),
+      const WidgetTest2(text: 'child 2'),
     ];
     await tester.pumpWidget(SwitchingChildListTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -122,9 +122,9 @@ void main() {
 
   testWidgets('Sliver with keep alive with Value key - should not dispose after reodering', (WidgetTester tester) async {
     List<Widget> childList= <Widget>[
-      WidgetTest0(text: 'child 0', key: const ValueKey<int>(0), keepAlive: true),
-      WidgetTest1(text: 'child 1', key: const ValueKey<int>(1), keepAlive: true),
-      WidgetTest2(text: 'child 2', key: const ValueKey<int>(2), keepAlive: true),
+      const WidgetTest0(text: 'child 0', key: ValueKey<int>(0), keepAlive: true),
+      const WidgetTest1(text: 'child 1', key: ValueKey<int>(1), keepAlive: true),
+      const WidgetTest2(text: 'child 2', key: ValueKey<int>(2), keepAlive: true),
     ];
     await tester.pumpWidget(SwitchingChildListTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -146,7 +146,7 @@ void main() {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: GlobalKey(), keepAlive: true),
       WidgetTest1(text: 'child 1', key: GlobalKey(), keepAlive: true),
-      WidgetTest2(text: 'child 2', keepAlive: true),
+      const WidgetTest2(text: 'child 2', keepAlive: true),
     ];
     await tester.pumpWidget(SwitchingChildListTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -190,7 +190,7 @@ void main() {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: GlobalKey(), keepAlive: true),
       WidgetTest1(text: 'child 1', key: UniqueKey()),
-      WidgetTest2(text: 'child 2', keepAlive: true),
+      const WidgetTest2(text: 'child 2', keepAlive: true),
     ];
     await tester.pumpWidget(SwitchingChildListTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -233,7 +233,7 @@ void main() {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: UniqueKey(), keepAlive: true),
       WidgetTest1(text: 'child 1', key: GlobalKey()),
-      WidgetTest2(text: 'child 2', keepAlive: true),
+      const WidgetTest2(text: 'child 2', keepAlive: true),
     ];
     await tester.pumpWidget(SwitchingChildBuilderTest(children: childList));
     final _WidgetTest0State state0 = tester.state(find.byType(WidgetTest0));
@@ -276,7 +276,7 @@ void main() {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: UniqueKey(), keepAlive: true),
       WidgetTest1(text: 'child 1', key: UniqueKey()),
-      WidgetTest2(text: 'child 2', keepAlive: true),
+      const WidgetTest2(text: 'child 2', keepAlive: true),
     ];
     await tester.pumpWidget(
         SwitchingChildListTest(children: childList, viewportFraction: 0.1)
@@ -316,7 +316,7 @@ void main() {
   testWidgets('SliverList should not dispose widget with key during in screen reordering', (WidgetTester tester) async {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: UniqueKey(), keepAlive: true),
-      WidgetTest1(text: 'child 1', keepAlive: true),
+      const WidgetTest1(text: 'child 1', keepAlive: true),
       WidgetTest2(text: 'child 2', key: UniqueKey()),
     ];
     await tester.pumpWidget(
@@ -366,7 +366,7 @@ void main() {
   testWidgets('SliverList remove child from child list', (WidgetTester tester) async {
     List<Widget> childList= <Widget>[
       WidgetTest0(text: 'child 0', key: UniqueKey(), keepAlive: true),
-      WidgetTest1(text: 'child 1', keepAlive: true),
+      const WidgetTest1(text: 'child 1', keepAlive: true),
       WidgetTest2(text: 'child 2', key: UniqueKey()),
     ];
     await tester.pumpWidget(
@@ -401,7 +401,7 @@ List<Widget> createSwitchedChildList(List<Widget> childList, int i, int j) {
 }
 
 class SwitchingChildBuilderTest extends StatefulWidget {
-  SwitchingChildBuilderTest({
+  const SwitchingChildBuilderTest({
     this.children,
     Key key
   }) : super(key: key);
@@ -474,7 +474,7 @@ class _SwitchingChildBuilderTest extends State<SwitchingChildBuilderTest> {
 }
 
 class SwitchingChildListTest extends StatefulWidget {
-  SwitchingChildListTest({
+  const SwitchingChildListTest({
     this.children,
     this.viewportFraction = 1.0,
     Key key
@@ -511,7 +511,7 @@ class _SwitchingChildListTest extends State<SwitchingChildListTest> {
 }
 
 class SwitchingSliverListTest extends StatefulWidget {
-  SwitchingSliverListTest({
+  const SwitchingSliverListTest({
     this.children,
     this.viewportFraction = 1.0,
     Key key
@@ -547,7 +547,7 @@ class _SwitchingSliverListTest extends State<SwitchingSliverListTest> {
 }
 
 class WidgetTest0 extends StatefulWidget {
-  WidgetTest0({
+  const WidgetTest0({
     this.text,
     this.keepAlive = false,
     Key key
@@ -580,7 +580,7 @@ class _WidgetTest0State extends State<WidgetTest0> with AutomaticKeepAliveClient
 }
 
 class WidgetTest1 extends StatefulWidget {
-  WidgetTest1({
+  const WidgetTest1({
     this.text,
     this.keepAlive = false,
     Key key
@@ -613,7 +613,7 @@ class _WidgetTest1State extends State<WidgetTest1> with AutomaticKeepAliveClient
 }
 
 class WidgetTest2 extends StatefulWidget {
-  WidgetTest2({
+  const WidgetTest2({
     this.text,
     this.keepAlive = false,
     Key key