more const for immutables (#10563)

examples/catalog/lib/animated_list.dart

@@ -152,7 +152,7 @@ class ListModel<E> {
 /// This widget's height is based on the animation parameter, it varies
 /// from 0 to 128 as the animation varies from 0.0 to 1.0.
 class CardItem extends StatelessWidget {
-  CardItem({
+  const CardItem({
     Key key,
     @required this.animation,
     this.onTap,

examples/catalog/lib/expansion_tile_sample.dart

@@ -68,7 +68,7 @@ final List<Entry> data = <Entry>[
 // Displays one Entry. If the entry has children then it's displayed
 // with an ExpansionTile.
 class EntryItem extends StatelessWidget {
-  EntryItem(this.entry);
+  const EntryItem(this.entry);
 
   final Entry entry;
 

examples/flutter_gallery/lib/demo/animation/home.dart

@@ -75,7 +75,7 @@ class _RenderStatusBarPaddingSliver extends RenderSliver {
 }
 
 class _StatusBarPaddingSliver extends SingleChildRenderObjectWidget {
-  _StatusBarPaddingSliver({
+  const _StatusBarPaddingSliver({
     Key key,
     @required this.maxHeight,
     this.scrollFactor: 5.0,
@@ -369,7 +369,7 @@ class _AllSectionsView extends AnimatedWidget {
 // app bar's height is _kAppBarMidHeight and only one section heading is
 // visible.
 class _SnappingScrollPhysics extends ClampingScrollPhysics {
-  _SnappingScrollPhysics({
+  const _SnappingScrollPhysics({
     ScrollPhysics parent,
     @required this.midScrollOffset,
   }) : assert(midScrollOffset != null),

examples/flutter_gallery/lib/demo/animation/widgets.dart

@@ -11,7 +11,7 @@ const double kSectionIndicatorWidth = 32.0;
 
 // The card for a single section. Displays the section's gradient and background image.
 class SectionCard extends StatelessWidget {
-  SectionCard({ Key key, @required this.section })
+  const SectionCard({ Key key, @required this.section })
     : assert(section != null),
       super(key: key);
 
@@ -60,7 +60,7 @@ class SectionTitle extends StatelessWidget {
     color: const Color(0x19000000),
   );
 
-  SectionTitle({
+  const SectionTitle({
     Key key,
     @required this.section,
     @required this.scale,

examples/flutter_gallery/lib/demo/colors_demo.dart

@@ -42,7 +42,7 @@ final List<Palette> allPalettes = <Palette>[
 
 
 class ColorItem extends StatelessWidget {
-  ColorItem({
+  const ColorItem({
     Key key,
     @required this.index,
     @required this.color,

examples/flutter_gallery/lib/demo/shrine/shrine_home.dart

@@ -116,7 +116,7 @@ class _ShrineGridDelegate extends SliverGridDelegate {
 
 // Displays the Vendor's name and avatar.
 class _VendorItem extends StatelessWidget {
-  _VendorItem({ Key key, @required this.vendor })
+  const _VendorItem({ Key key, @required this.vendor })
     : assert(vendor != null),
       super(key: key);
 
@@ -294,7 +294,7 @@ class _Heading extends StatelessWidget {
 // A card that displays a product's image, price, and vendor. The _ProductItem
 // cards appear in a grid below the heading.
 class _ProductItem extends StatelessWidget {
-  _ProductItem({ Key key, @required this.product, this.onPressed })
+  const _ProductItem({ Key key, @required this.product, this.onPressed })
     : assert(product != null),
       super(key: key);
 

examples/flutter_gallery/lib/demo/shrine/shrine_order.dart

@@ -12,7 +12,7 @@ import 'shrine_types.dart';
 
 // Displays the product title's, description, and order quantity dropdown.
 class _ProductItem extends StatelessWidget {
-  _ProductItem({
+  const _ProductItem({
     Key key,
     @required this.product,
     @required this.quantity,
@@ -69,7 +69,7 @@ class _ProductItem extends StatelessWidget {
 
 // Vendor name and description
 class _VendorItem extends StatelessWidget {
-  _VendorItem({ Key key, @required this.vendor })
+  const _VendorItem({ Key key, @required this.vendor })
     : assert(vendor != null),
       super(key: key);
 
@@ -140,7 +140,7 @@ class _HeadingLayout extends MultiChildLayoutDelegate {
 // Describes a product and vendor in detail, supports specifying
 // a order quantity (0-5). Appears at the top of the OrderPage.
 class _Heading extends StatelessWidget {
-  _Heading({
+  const _Heading({
     Key key,
     @required this.product,
     @required this.quantity,

examples/flutter_gallery/lib/demo/shrine/shrine_page.dart

@@ -15,7 +15,7 @@ enum ShrineAction {
 }
 
 class ShrinePage extends StatefulWidget {
-  ShrinePage({
+  const ShrinePage({
     Key key,
     @required this.scaffoldKey,
     @required this.body,

examples/flutter_gallery/lib/demo/typography_demo.dart

@@ -6,7 +6,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 class TextStyleItem extends StatelessWidget {
-  TextStyleItem({
+  const TextStyleItem({
     Key key,
     @required this.name,
     @required this.style,

examples/flutter_gallery/lib/gallery/drawer.dart

@@ -88,7 +88,7 @@ class _GalleryDrawerHeaderState extends State<GalleryDrawerHeader> {
 }
 
 class GalleryDrawer extends StatelessWidget {
-  GalleryDrawer({
+  const GalleryDrawer({
     Key key,
     this.useLightTheme,
     @required this.onThemeChanged,

examples/flutter_gallery/lib/gallery/home.dart

@@ -66,7 +66,7 @@ class _AppBarBackground extends StatelessWidget {
 }
 
 class GalleryHome extends StatefulWidget {
-  GalleryHome({
+  const GalleryHome({
     Key key,
     this.useLightTheme,
     @required this.onThemeChanged,

examples/flutter_gallery/lib/gallery/item.dart

@@ -12,7 +12,7 @@ import '../demo/all.dart';
 typedef Widget GalleryDemoBuilder();
 
 class GalleryItem extends StatelessWidget {
-  GalleryItem({
+  const GalleryItem({
     @required this.title,
     this.subtitle,
     @required this.category,

examples/flutter_gallery/lib/gallery/updates.dart

@@ -12,7 +12,7 @@ import 'package:url_launcher/url_launcher.dart';
 typedef Future<String> UpdateUrlFetcher();
 
 class Updater extends StatefulWidget {
-  Updater({ @required this.updateUrlFetcher, this.child, Key key })
+  const Updater({ @required this.updateUrlFetcher, this.child, Key key })
     : assert(updateUrlFetcher != null),
       super(key: key);
 

examples/platform_view/lib/main.dart

@@ -19,13 +19,13 @@ class PlatformView extends StatelessWidget {
       theme: new ThemeData(
         primarySwatch: Colors.grey,
       ),
-      home: new MyHomePage(title: 'Platform View'),
+      home: const MyHomePage(title: 'Platform View'),
     );
   }
 }
 
 class MyHomePage extends StatefulWidget {
-  MyHomePage({Key key, this.title}) : super(key: key);
+  const MyHomePage({Key key, this.title}) : super(key: key);
 
   final String title;
 

packages/flutter/lib/src/services/message_codec.dart

@@ -35,7 +35,7 @@ abstract class MessageCodec<T> {
 class MethodCall {
   /// Creates a [MethodCall] representing the invocation of [method] with the
   /// specified [arguments].
-  MethodCall(this.method, [this.arguments])
+  const MethodCall(this.method, [this.arguments])
     : assert(method != null);
 
   /// The name of the method to be called.

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

@@ -46,7 +46,7 @@ class _ActiveItem implements Comparable<_ActiveItem> {
 /// This widget is similar to one created by [ListView.builder].
 class AnimatedList extends StatefulWidget {
   /// Creates a scrolling container that animates items when they are inserted or removed.
-  AnimatedList({
+  const AnimatedList({
     Key key,
     @required this.itemBuilder,
     this.initialItemCount: 0,

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

@@ -195,7 +195,7 @@ class AsyncSnapshot<T> {
   const AsyncSnapshot.nothing() : this._(ConnectionState.none, null, null);
 
   /// Creates an [AsyncSnapshot] in the specified [state] and with the specified [data].
-  AsyncSnapshot.withData(ConnectionState state, T data) : this._(state, data, null); // not const because https://github.com/dart-lang/sdk/issues/29432
+  const AsyncSnapshot.withData(ConnectionState state, T data) : this._(state, data, null);
 
   /// Creates an [AsyncSnapshot] in the specified [state] and with the specified [error].
   const AsyncSnapshot.withError(ConnectionState state, Object error) : this._(state, null, error);

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

@@ -313,10 +313,10 @@ class LabeledGlobalKey<T extends State<StatefulWidget>> extends GlobalKey<T> {
   /// Creates a global key with a debugging label.
   ///
   /// The label does not affect the key's identity.
-  const LabeledGlobalKey(this._debugLabel) : super.constructor();
+  LabeledGlobalKey(this._debugLabel) : super.constructor();
 
   // Used for forwarding the constructor from GlobalKey.
-  const LabeledGlobalKey._({ String debugLabel }) : _debugLabel = debugLabel, super.constructor();
+  LabeledGlobalKey._({ String debugLabel }) : _debugLabel = debugLabel, super.constructor();
 
   final String _debugLabel;
 

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

@@ -36,7 +36,7 @@ typedef List<Widget> NestedScrollViewHeaderSliversBuilder(BuildContext context,
 const double _kInitialScrollOffset = 0.0;
 
 class NestedScrollView extends StatefulWidget {
-  NestedScrollView({
+  const NestedScrollView({
     Key key,
     this.scrollDirection: Axis.vertical,
     this.reverse: false,

packages/flutter/test/services/haptic_feedback_test.dart

@@ -15,6 +15,6 @@ void main() {
 
     await HapticFeedback.vibrate();
 
-    expect(log, equals(<MethodCall>[new MethodCall('HapticFeedback.vibrate')]));
+    expect(log, equals(<MethodCall>[const MethodCall('HapticFeedback.vibrate')]));
   });
 }

packages/flutter/test/services/platform_channel_test.dart

@@ -91,7 +91,7 @@ void main() {
     });
     test('can handle method call with no registered plugin', () async {
       channel.setMethodCallHandler(null);
-      final ByteData call = jsonMethod.encodeMethodCall(new MethodCall('sayHello', 'hello'));
+      final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData envelope;
       await BinaryMessages.handlePlatformMessage('ch7', call, (ByteData result) {
         envelope = result;
@@ -102,7 +102,7 @@ void main() {
       channel.setMethodCallHandler((MethodCall call) async {
         throw new MissingPluginException();
       });
-      final ByteData call = jsonMethod.encodeMethodCall(new MethodCall('sayHello', 'hello'));
+      final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData envelope;
       await BinaryMessages.handlePlatformMessage('ch7', call, (ByteData result) {
         envelope = result;
@@ -111,7 +111,7 @@ void main() {
     });
     test('can handle method call with successful result', () async {
       channel.setMethodCallHandler((MethodCall call) async => '${call.arguments}, world');
-      final ByteData call = jsonMethod.encodeMethodCall(new MethodCall('sayHello', 'hello'));
+      final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData envelope;
       await BinaryMessages.handlePlatformMessage('ch7', call, (ByteData result) {
         envelope = result;
@@ -122,7 +122,7 @@ void main() {
       channel.setMethodCallHandler((MethodCall call) async {
         throw new PlatformException(code: 'bad', message: 'sayHello failed', details: null);
       });
-      final ByteData call = jsonMethod.encodeMethodCall(new MethodCall('sayHello', 'hello'));
+      final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData envelope;
       await BinaryMessages.handlePlatformMessage('ch7', call, (ByteData result) {
         envelope = result;
@@ -141,7 +141,7 @@ void main() {
       channel.setMethodCallHandler((MethodCall call) async {
         throw new ArgumentError('bad');
       });
-      final ByteData call = jsonMethod.encodeMethodCall(new MethodCall('sayHello', 'hello'));
+      final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData envelope;
       await BinaryMessages.handlePlatformMessage('ch7', call, (ByteData result) {
         envelope = result;

packages/flutter/test/services/system_navigator_test.dart

@@ -15,6 +15,6 @@ void main() {
 
     await SystemNavigator.pop();
 
-    expect(log, equals(<MethodCall>[new MethodCall('SystemNavigator.pop')]));
+    expect(log, equals(<MethodCall>[const MethodCall('SystemNavigator.pop')]));
   });
 }

packages/flutter/test/services/system_sound_test.dart

@@ -8,13 +8,13 @@ import 'package:test/test.dart';
 void main() {
   test('System sound control test', () async {
     final List<MethodCall> log = <MethodCall>[];
-  
+
     SystemChannels.platform.setMockMethodCallHandler((MethodCall methodCall) async {
       log.add(methodCall);
     });
-  
+
     await SystemSound.play(SystemSoundType.click);
 
-    expect(log, equals(<MethodCall>[new MethodCall('SystemSound.play', "SystemSoundType.click")]));
+    expect(log, equals(<MethodCall>[const MethodCall('SystemSound.play', "SystemSoundType.click")]));
   });
 }

packages/flutter/test/widgets/async_test.dart

@@ -14,7 +14,7 @@ void main() {
   group('AsyncSnapshot', () {
     test('requiring data succeeds if data is present', () {
       expect(
-        new AsyncSnapshot<String>.withData(ConnectionState.done, 'hello').requireData,
+        const AsyncSnapshot<String>.withData(ConnectionState.done, 'hello').requireData,
         'hello',
       );
     });

packages/flutter/test/widgets/layout_builder_mutations_test.dart

@@ -9,7 +9,7 @@ import 'package:flutter/src/widgets/layout_builder.dart';
 import 'package:flutter_test/flutter_test.dart' hide TypeMatcher;
 
 class Wrapper extends StatelessWidget {
-  Wrapper({
+  const Wrapper({
     Key key,
     @required this.child
   }) : assert(child != null),