prefer const constructors (#8316)

dev/benchmarks/complex_layout/lib/main.dart

@@ -73,7 +73,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
         children: <Widget>[
           new Expanded(
             child: new ListView.builder(
-              key: new Key('main-scroll'), // this key is used by the driver test
+              key: const Key('main-scroll'), // this key is used by the driver test
               itemBuilder: (BuildContext context, int index) {
                 if (index % 2 == 0)
                   return new FancyImageItem(index, key: new ValueKey<int>(index));
@@ -154,7 +154,7 @@ class MenuItemWithIcon extends StatelessWidget {
       children: <Widget>[
         new Icon(icon),
         new Padding(
-          padding: new EdgeInsets.only(left: 8.0, right: 8.0),
+          padding: const EdgeInsets.only(left: 8.0, right: 8.0),
           child: new Text(title)
         ),
         new Text(subtitle, style: Theme.of(context).textTheme.caption)
@@ -177,7 +177,7 @@ class FancyImageItem extends StatelessWidget {
         new ItemImageBox(),
         new InfoBar(),
         new Padding(
-          padding: new EdgeInsets.symmetric(horizontal: 8.0),
+          padding: const EdgeInsets.symmetric(horizontal: 8.0),
           child: new Divider()
         ),
         new IconBar(),
@@ -199,7 +199,7 @@ class FancyGalleryItem extends StatelessWidget {
         new ItemGalleryBox(index),
         new InfoBar(),
         new Padding(
-          padding: new EdgeInsets.symmetric(horizontal: 8.0),
+          padding: const EdgeInsets.symmetric(horizontal: 8.0),
           child: new Divider()
         ),
         new IconBar(),
@@ -213,7 +213,7 @@ class InfoBar extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.all(8.0),
+      padding: const EdgeInsets.all(8.0),
       child: new Row(
         mainAxisAlignment: MainAxisAlignment.spaceBetween,
         children: <Widget>[
@@ -229,7 +229,7 @@ class IconBar extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.only(left: 16.0, right: 16.0),
+      padding: const EdgeInsets.only(left: 16.0, right: 16.0),
       child: new Row(
         mainAxisAlignment: MainAxisAlignment.spaceBetween,
         children: <Widget>[
@@ -275,7 +275,7 @@ class MiniIconWithText extends StatelessWidget {
       mainAxisSize: MainAxisSize.min,
       children: <Widget>[
         new Padding(
-          padding: new EdgeInsets.only(right: 8.0),
+          padding: const EdgeInsets.only(right: 8.0),
           child: new Container(
             width: 16.0,
             height: 16.0,
@@ -312,12 +312,12 @@ class UserHeader extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.all(8.0),
+      padding: const EdgeInsets.all(8.0),
       child: new Row(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: <Widget>[
           new Padding(
-            padding: new EdgeInsets.only(right: 8.0),
+            padding: const EdgeInsets.only(right: 8.0),
             child: new Image(
               image: new AssetImage('packages/flutter_gallery_assets/ali_connors_sml.png'),
               width: 32.0,
@@ -332,9 +332,9 @@ class UserHeader extends StatelessWidget {
                 new RichText(text: new TextSpan(
                   style: Theme.of(context).textTheme.body1,
                   children: <TextSpan>[
-                    new TextSpan(text: userName, style: new TextStyle(fontWeight: FontWeight.bold)),
-                    new TextSpan(text: ' shared a new '),
-                    new TextSpan(text: 'photo', style: new TextStyle(fontWeight: FontWeight.bold))
+                    new TextSpan(text: userName, style: const TextStyle(fontWeight: FontWeight.bold)),
+                    const TextSpan(text: ' shared a new '),
+                    const TextSpan(text: 'photo', style: const TextStyle(fontWeight: FontWeight.bold))
                   ]
                 )),
                 new Row(
@@ -357,7 +357,7 @@ class ItemDescription extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.all(8.0),
+      padding: const EdgeInsets.all(8.0),
       child: new Text('Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.')
     );
   }
@@ -367,7 +367,7 @@ class ItemImageBox extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.all(8.0),
+      padding: const EdgeInsets.all(8.0),
       child: new Card(
         child: new Column(
           crossAxisAlignment: CrossAxisAlignment.stretch,
@@ -404,16 +404,16 @@ class ItemImageBox extends StatelessWidget {
                       backgroundColor: Colors.black54,
                       borderRadius: new BorderRadius.circular(2.0)
                     ),
-                    padding: new EdgeInsets.all(4.0),
+                    padding: const EdgeInsets.all(4.0),
                     child: new RichText(
                       text: new TextSpan(
-                        style: new TextStyle(color: Colors.white),
+                        style: const TextStyle(color: Colors.white),
                         children: <TextSpan>[
-                          new TextSpan(
+                          const TextSpan(
                             text: 'Photo by '
                           ),
-                          new TextSpan(
-                            style: new TextStyle(fontWeight: FontWeight.bold),
+                          const TextSpan(
+                            style: const TextStyle(fontWeight: FontWeight.bold),
                             text: 'Magic Mike'
                           )
                         ]
@@ -425,7 +425,7 @@ class ItemImageBox extends StatelessWidget {
             )
             ,
             new Padding(
-              padding: new EdgeInsets.all(8.0),
+              padding: const EdgeInsets.all(8.0),
               child: new Column(
                 crossAxisAlignment: CrossAxisAlignment.stretch,
                 children: <Widget>[
@@ -465,7 +465,7 @@ class ItemGalleryBox extends StatelessWidget {
                   return new Container(
                     key: new Key(tabName),
                     child: new Padding(
-                      padding: new EdgeInsets.all(8.0),
+                      padding: const EdgeInsets.all(8.0),
                       child: new Card(
                         child: new Column(
                           children: <Widget>[
@@ -491,7 +491,7 @@ class ItemGalleryBox extends StatelessWidget {
                                 ),
                                 new Expanded(
                                   child: new Padding(
-                                    padding: new EdgeInsets.only(left: 8.0),
+                                    padding: const EdgeInsets.only(left: 8.0),
                                     child: new Text('This is item $tabName'),
                                   )
                                 )
@@ -550,7 +550,7 @@ class BottomBarButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Padding(
-      padding: new EdgeInsets.all(8.0),
+      padding: const EdgeInsets.all(8.0),
       child: new Column(
         children: <Widget>[
           new IconButton(

dev/benchmarks/complex_layout/test_driver/scroll_perf_test.dart

@@ -27,14 +27,14 @@ void main() {
 
         // Scroll down
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, -300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, -300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
 
         // Scroll up
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, 300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, 300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
       });
 

dev/benchmarks/microbenchmarks/lib/stocks/build_bench.dart

@@ -31,7 +31,7 @@ Future<Null> main() async {
     stocks.main();
     await tester.pump(); // Start startup animation
     await tester.pump(const Duration(seconds: 1)); // Complete startup animation
-    await tester.tapAt(new Point(20.0, 40.0)); // Open drawer
+    await tester.tapAt(const Point(20.0, 40.0)); // Open drawer
     await tester.pump(); // Start drawer animation
     await tester.pump(const Duration(seconds: 1)); // Complete drawer animation
 

dev/benchmarks/microbenchmarks/lib/stocks/layout_bench.dart

@@ -30,7 +30,7 @@ Future<Null> main() async {
     stocks.main();
     await tester.pump(); // Start startup animation
     await tester.pump(const Duration(seconds: 1)); // Complete startup animation
-    await tester.tapAt(new Point(20.0, 40.0)); // Open drawer
+    await tester.tapAt(const Point(20.0, 40.0)); // Open drawer
     await tester.pump(); // Start drawer animation
     await tester.pump(const Duration(seconds: 1)); // Complete drawer animation
 

dev/devicelab/bin/run.dart

@@ -63,7 +63,7 @@ Future<Null> main(List<String> rawArgs) async {
       exitCode = 1;
 
     print('Task result:');
-    print(new JsonEncoder.withIndent('  ').convert(result));
+    print(const JsonEncoder.withIndent('  ').convert(result));
     section('Finished task "$taskName"');
   }
 }
@@ -115,7 +115,7 @@ final ArgParser _argParser = new ArgParser()
     splitCommas: true,
     callback: (List<String> value) {
       if (value.isNotEmpty) {
-        throw new FormatException(
+        throw const FormatException(
           'Invalid option --test. Did you mean --task (-t)?',
         );
       }

dev/devicelab/lib/framework/runner.dart

@@ -42,8 +42,8 @@ Future<Map<String, dynamic>> runTask(String taskName, { bool silent: false }) as
   });
 
   StreamSubscription<String> stdoutSub = runner.stdout
-      .transform(new Utf8Decoder())
-      .transform(new LineSplitter())
+      .transform(const Utf8Decoder())
+      .transform(const LineSplitter())
       .listen((String line) {
     if (!silent) {
       stdout.writeln('[$taskName] [STDOUT] $line');
@@ -51,8 +51,8 @@ Future<Map<String, dynamic>> runTask(String taskName, { bool silent: false }) as
   });
 
   StreamSubscription<String> stderrSub = runner.stderr
-      .transform(new Utf8Decoder())
-      .transform(new LineSplitter())
+      .transform(const Utf8Decoder())
+      .transform(const LineSplitter())
       .listen((String line) {
     stderr.writeln('[$taskName] [STDERR] $line');
   });

dev/devicelab/lib/framework/utils.dart

@@ -318,7 +318,7 @@ T requireConfigProperty<T>(Map<String, dynamic> map, String propertyName) {
 }
 
 String jsonEncode(dynamic data) {
-  return new JsonEncoder.withIndent('  ').convert(data) + '\n';
+  return const JsonEncoder.withIndent('  ').convert(data) + '\n';
 }
 
 Future<Null> getFlutter(String revision) async {

dev/devicelab/lib/tasks/perf_tests.dart

@@ -305,12 +305,12 @@ class AndroidBackButtonMemoryTest {
       // Perform a series of back button suspend and resume cycles.
       for (int i = 0; i < 10; i++) {
         await device.shellExec('input', <String>['keyevent', 'KEYCODE_BACK']);
-        await new Future<Null>.delayed(new Duration(milliseconds: 1000));
+        await new Future<Null>.delayed(const Duration(milliseconds: 1000));
         String output = await device.shellEval('am', <String>['start', '-n', 'io.flutter.examples.gallery/io.flutter.app.FlutterActivity']);
         print(output);
         if (output.contains('Error'))
           return new TaskResult.failure('unable to launch activity');
-        await new Future<Null>.delayed(new Duration(milliseconds: 1000));
+        await new Future<Null>.delayed(const Duration(milliseconds: 1000));
       }
 
       Map<String, dynamic> endData = await device.getMemoryStats(packageName);

dev/manual_tests/drag_and_drop.dart

@@ -27,7 +27,7 @@ class ExampleDragTargetState extends State<ExampleDragTarget> {
       builder: (BuildContext context, List<Color> data, List<dynamic> rejectedData) {
         return new Container(
           height: 100.0,
-          margin: new EdgeInsets.all(10.0),
+          margin: const EdgeInsets.all(10.0),
           decoration: new BoxDecoration(
             border: new Border.all(
               width: 3.0,

dev/manual_tests/overlay_geometry.dart

@@ -169,7 +169,7 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
     setState(() {
       markers[MarkerType.touch] = globalPosition;
       final RenderBox box = target.currentContext.findRenderObject();
-      markers[MarkerType.topLeft] = box.localToGlobal(new Point(0.0, 0.0));
+      markers[MarkerType.topLeft] = box.localToGlobal(const Point(0.0, 0.0));
       final Size size = box.size;
       markers[MarkerType.bottomRight] = box.localToGlobal(new Point(size.width, size.height));
       final ScrollableState scrollable = Scrollable.of(target.currentContext);

dev/manual_tests/page_view.dart

@@ -40,7 +40,7 @@ class PageViewAppState extends State<PageViewApp> {
     const TextStyle(color: Colors.white, fontSize: 18.0, fontWeight: FontWeight.bold);
 
   List<CardModel> cardModels;
-  Size pageSize = new Size(200.0, 200.0);
+  Size pageSize = const Size(200.0, 200.0);
   Axis scrollDirection = Axis.horizontal;
   bool itemsWrap = false;
 

examples/flutter_gallery/lib/demo/buttons_demo.dart

@@ -90,7 +90,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildRaisedButton() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new ButtonBar(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -111,7 +111,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildFlatButton() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new ButtonBar(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -158,7 +158,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
               }).toList(),
             ),
           ),
-          new SizedBox(
+          const SizedBox(
             height: 24.0,
           ),
           new ListItem(
@@ -179,7 +179,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
               }).toList(),
             ),
           ),
-          new SizedBox(
+          const SizedBox(
             height: 24.0,
           ),
           new ListItem(
@@ -213,7 +213,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildIconButton() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -237,7 +237,7 @@ class _ButtonsDemoState extends State<ButtonsDemo> {
 
   Widget buildActionButton() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new FloatingActionButton(
         child: new Icon(Icons.add),
         onPressed: () {

examples/flutter_gallery/lib/demo/date_and_time_picker_demo.dart

@@ -95,7 +95,7 @@ class _DateTimePicker extends StatelessWidget {
             onPressed: () { _selectDate(context); },
           ),
         ),
-        new SizedBox(width: 12.0),
+        const SizedBox(width: 12.0),
         new Expanded(
           flex: 3,
           child: new _InputDropdown(

examples/flutter_gallery/lib/demo/icons_demo.dart

@@ -122,7 +122,7 @@ class IconsDemoState extends State<IconsDemo> {
               new Expanded(
                 child: new Center(
                   child: new IconTheme(
-                    data: new IconThemeData(opacity: 1.0),
+                    data: const IconThemeData(opacity: 1.0),
                     child: new Row(
                       mainAxisAlignment: MainAxisAlignment.center,
                       children: <Widget>[

examples/flutter_gallery/lib/demo/overscroll_demo.dart

@@ -26,7 +26,7 @@ class OverscrollDemoState extends State<OverscrollDemo> {
 
   Future<Null> _handleRefresh() {
     Completer<Null> completer = new Completer<Null>();
-    new Timer(new Duration(seconds: 3), () { completer.complete(null); });
+    new Timer(const Duration(seconds: 3), () { completer.complete(null); });
     return completer.future.then((_) {
        _scaffoldKey.currentState?.showSnackBar(new SnackBar(
          content: new Text("Refresh complete"),

examples/flutter_gallery/lib/demo/pesto_demo.dart

@@ -140,7 +140,7 @@ class _RecipeGridPageState extends State<RecipeGridPage> {
     return new SliverPadding(
       padding: padding,
       child: new SliverGrid(
-        gridDelegate: new SliverGridDelegateWithMaxCrossAxisExtent(
+        gridDelegate: const SliverGridDelegateWithMaxCrossAxisExtent(
           maxCrossAxisExtent: _kRecipePageMaxWidth,
           crossAxisSpacing: 8.0,
           mainAxisSpacing: 8.0,
@@ -299,7 +299,7 @@ class RecipePage extends StatefulWidget {
 
 class _RecipePageState extends State<RecipePage> {
   final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
-  final TextStyle menuItemStyle = new PestoStyle(fontSize: 15.0, color: Colors.black54, height: 24.0/15.0);
+  final TextStyle menuItemStyle = const PestoStyle(fontSize: 15.0, color: Colors.black54, height: 24.0/15.0);
 
   double _getAppBarHeight(BuildContext context) => MediaQuery.of(context).size.height * 0.3;
 
@@ -448,7 +448,7 @@ class RecipeSheet extends StatelessWidget {
             ),
             new TableRow(
               children: <Widget>[
-                new SizedBox(),
+                const SizedBox(),
                 new Padding(
                   padding: const EdgeInsets.only(top: 8.0, bottom: 4.0),
                   child: new Text(recipe.description, style: descriptionStyle)
@@ -457,7 +457,7 @@ class RecipeSheet extends StatelessWidget {
             ),
             new TableRow(
               children: <Widget>[
-                new SizedBox(),
+                const SizedBox(),
                 new Padding(
                   padding: const EdgeInsets.only(top: 24.0, bottom: 4.0),
                   child: new Text('Ingredients', style: headingStyle)
@@ -471,7 +471,7 @@ class RecipeSheet extends StatelessWidget {
           ))..add(
             new TableRow(
               children: <Widget>[
-                new SizedBox(),
+                const SizedBox(),
                 new Padding(
                   padding: const EdgeInsets.only(top: 24.0, bottom: 4.0),
                   child: new Text('Steps', style: headingStyle)

examples/flutter_gallery/lib/demo/selection_controls_demo.dart

@@ -75,7 +75,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildCheckbox() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new Column(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -109,7 +109,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildRadio() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new Column(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[
@@ -161,7 +161,7 @@ class _SelectionControlsDemoState extends State<SelectionControlsDemo> {
 
   Widget buildSwitch() {
     return new Align(
-      alignment: new FractionalOffset(0.5, 0.4),
+      alignment: const FractionalOffset(0.5, 0.4),
       child: new Row(
         mainAxisSize: MainAxisSize.min,
         children: <Widget>[

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

@@ -135,7 +135,7 @@ class VendorItem extends StatelessWidget {
               child: new Image.asset(vendor.avatarAsset, fit: ImageFit.cover),
             ),
           ),
-          new SizedBox(width: 8.0),
+          const SizedBox(width: 8.0),
           new Expanded(
             child: new Text(vendor.name, style: ShrineTheme.of(context).vendorItemStyle),
           ),

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

@@ -43,7 +43,7 @@ class OrderItem extends StatelessWidget {
                 ),
               ),
             ),
-            new SizedBox(height: 24.0),
+            const SizedBox(height: 24.0),
             new Row(
               children: <Widget>[
                 new Padding(
@@ -66,9 +66,9 @@ class OrderItem extends StatelessWidget {
               child: new Column(
                 crossAxisAlignment: CrossAxisAlignment.stretch,
                 children: <Widget>[
-                  new SizedBox(height: 24.0),
+                  const SizedBox(height: 24.0),
                   new Text(product.description, style: theme.featureStyle),
-                  new SizedBox(height: 16.0),
+                  const SizedBox(height: 16.0),
                   new Padding(
                     padding: const EdgeInsets.only(top: 8.0, bottom: 8.0, right: 88.0),
                     child: new DropdownButtonHideUnderline(
@@ -94,7 +94,7 @@ class OrderItem extends StatelessWidget {
                       ),
                     ),
                   ),
-                  new SizedBox(height: 16.0),
+                  const SizedBox(height: 16.0),
                   new SizedBox(
                     height: 24.0,
                     child: new Align(
@@ -102,9 +102,9 @@ class OrderItem extends StatelessWidget {
                       child: new Text(product.vendor.name, style: theme.vendorTitleStyle),
                     ),
                   ),
-                  new SizedBox(height: 16.0),
+                  const SizedBox(height: 16.0),
                   new Text(product.vendor.description, style: theme.vendorStyle),
-                  new SizedBox(height: 24.0),
+                  const SizedBox(height: 24.0),
                 ],
               ),
             ),
@@ -186,13 +186,13 @@ class _OrderPageState extends State<OrderPage> {
                 quantity: currentOrder.quantity,
                 quantityChanged: (int value) { updateOrder(quantity: value); },
               ),
-              new SizedBox(height: 24.0),
+              const SizedBox(height: 24.0),
             ]),
           ),
           new SliverPadding(
             padding: const EdgeInsets.all(8.0),
             child: new SliverGrid(
-              gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
+              gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                 crossAxisCount: 2,
                 mainAxisSpacing: 8.0,
                 crossAxisSpacing: 8.0,

examples/flutter_gallery/lib/demo/shrine_demo.dart

@@ -14,7 +14,7 @@ Widget buildShrine(BuildContext context, Widget child) {
   return new Theme(
     data: new ThemeData(
       primarySwatch: Colors.grey,
-      iconTheme: new IconThemeData(color: const Color(0xFF707070)),
+      iconTheme: const IconThemeData(color: const Color(0xFF707070)),
       platform: Theme.of(context).platform,
     ),
     child: new ShrineTheme(child: child)

examples/flutter_gallery/lib/demo/text_field_demo.dart

@@ -145,7 +145,7 @@ class TextFieldDemoState extends State<TextFieldDemo> {
                     onSaved: (InputValue val) { person.password = val.text; }
                   )
                 ),
-                new SizedBox(width: 16.0),
+                const SizedBox(width: 16.0),
                 new Expanded(
                   child: new TextField(
                     hintText: 'How do you log in?',

examples/flutter_gallery/lib/gallery/demo.dart

@@ -134,10 +134,10 @@ class FullScreenCodeDialogState extends State<FullScreenCodeDialog> {
     } else {
       body = new SingleChildScrollView(
         child: new Padding(
-          padding: new EdgeInsets.all(16.0),
+          padding: const EdgeInsets.all(16.0),
           child: new RichText(
             text: new TextSpan(
-              style: new TextStyle(fontFamily: 'monospace', fontSize: 10.0),
+              style: const TextStyle(fontFamily: 'monospace', fontSize: 10.0),
               children: <TextSpan>[
                 new DartSyntaxHighlighter(style).format(_exampleCode)
               ]

examples/flutter_gallery/lib/gallery/drawer.dart

@@ -215,9 +215,9 @@ class GalleryDrawer extends StatelessWidget {
     );
 
     final Widget aboutItem = new AboutDrawerItem(
-      icon: new FlutterLogo(),
+      icon: const FlutterLogo(),
       applicationVersion: '2016 Q3 Preview',
-      applicationIcon: new FlutterLogo(),
+      applicationIcon: const FlutterLogo(),
       applicationLegalese: '© 2016 The Chromium Authors',
       aboutBoxChildren: <Widget>[
         new Padding(

examples/flutter_gallery/lib/gallery/syntax_highlighter.dart

@@ -19,27 +19,27 @@ class SyntaxHighlighterStyle {
 
   static SyntaxHighlighterStyle lightThemeStyle() {
     return new SyntaxHighlighterStyle(
-      baseStyle: new TextStyle(color: const Color(0xFF000000)),
-      numberStyle: new TextStyle(color: const Color(0xFF1565C0)),
-      commentStyle: new TextStyle(color: const Color(0xFF9E9E9E)),
-      keywordStyle: new TextStyle(color: const Color(0xFF9C27B0)),
-      stringStyle: new TextStyle(color: const Color(0xFF43A047)),
-      punctuationStyle: new TextStyle(color: const Color(0xFF000000)),
-      classStyle: new TextStyle(color: const Color(0xFF512DA8)),
-      constantStyle: new TextStyle(color: const Color(0xFF795548))
+      baseStyle: const TextStyle(color: const Color(0xFF000000)),
+      numberStyle: const TextStyle(color: const Color(0xFF1565C0)),
+      commentStyle: const TextStyle(color: const Color(0xFF9E9E9E)),
+      keywordStyle: const TextStyle(color: const Color(0xFF9C27B0)),
+      stringStyle: const TextStyle(color: const Color(0xFF43A047)),
+      punctuationStyle: const TextStyle(color: const Color(0xFF000000)),
+      classStyle: const TextStyle(color: const Color(0xFF512DA8)),
+      constantStyle: const TextStyle(color: const Color(0xFF795548))
     );
   }
 
   static SyntaxHighlighterStyle darkThemeStyle() {
     return new SyntaxHighlighterStyle(
-      baseStyle: new TextStyle(color: const Color(0xFFFFFFFF)),
-      numberStyle: new TextStyle(color: const Color(0xFF1565C0)),
-      commentStyle: new TextStyle(color: const Color(0xFF9E9E9E)),
-      keywordStyle: new TextStyle(color: const Color(0xFF80CBC4)),
-      stringStyle: new TextStyle(color: const Color(0xFF009688)),
-      punctuationStyle: new TextStyle(color: const Color(0xFFFFFFFF)),
-      classStyle: new TextStyle(color: const Color(0xFF009688)),
-      constantStyle: new TextStyle(color: const Color(0xFF795548))
+      baseStyle: const TextStyle(color: const Color(0xFFFFFFFF)),
+      numberStyle: const TextStyle(color: const Color(0xFF1565C0)),
+      commentStyle: const TextStyle(color: const Color(0xFF9E9E9E)),
+      keywordStyle: const TextStyle(color: const Color(0xFF80CBC4)),
+      stringStyle: const TextStyle(color: const Color(0xFF009688)),
+      punctuationStyle: const TextStyle(color: const Color(0xFFFFFFFF)),
+      classStyle: const TextStyle(color: const Color(0xFF009688)),
+      constantStyle: const TextStyle(color: const Color(0xFF795548))
     );
   }
 

examples/flutter_gallery/lib/gallery/updates.dart

@@ -32,7 +32,7 @@ class UpdaterState extends State<Updater> {
   Future<Null> _checkForUpdates() async {
     // Only prompt once a day
     if (_lastUpdateCheck != null &&
-        new DateTime.now().difference(_lastUpdateCheck) < new Duration(days: 1)) {
+        new DateTime.now().difference(_lastUpdateCheck) < const Duration(days: 1)) {
       return; // We already checked for updates recently
     }
     _lastUpdateCheck = new DateTime.now();

examples/flutter_gallery/test/example_code_display_test.dart

@@ -23,7 +23,7 @@ void main() {
     final Point allDemosOrigin = tester.getTopRight(find.text('Demos'));
     final Finder button = find.text('Buttons');
     while (button.evaluate().isEmpty) {
-      await tester.scrollAt(allDemosOrigin, new Offset(0.0, -100.0));
+      await tester.scrollAt(allDemosOrigin, const Offset(0.0, -100.0));
       await tester.pump(); // start the scroll
       await tester.pump(const Duration(seconds: 1));
     }

examples/flutter_gallery/test_driver/memory_nav_test.dart

@@ -37,6 +37,6 @@ void main() {
         await new Future<Null>.delayed(kWaitBetweenActions);
       }
       await completer.future;
-    }, timeout: new Timeout(new Duration(minutes: 1)));
+    }, timeout: const Timeout(const Duration(minutes: 1)));
   });
 }

examples/flutter_gallery/test_driver/scroll_perf_test.dart

@@ -34,14 +34,14 @@ void main() {
         // https://github.com/flutter/flutter/issues/3316
         // Scroll down
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, -300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, -300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
 
         // Scroll up
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, 300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, 300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
       });
 

examples/flutter_gallery/test_driver/transitions_perf_test.dart

@@ -56,7 +56,7 @@ final List<String> unsynchedDemoTitles = <String>[
   'Progress indicators',
 ];
 
-final FileSystem _fs = new LocalFileSystem();
+final FileSystem _fs = const LocalFileSystem();
 
 const Duration kWaitBetweenActions = const Duration(milliseconds: 250);
 
@@ -123,7 +123,7 @@ Future<Null> saveDurationsHistogram(List<Map<String, dynamic>> events, String ou
 
   // Save the durations Map to a file.
   final File file = await _fs.file(outputPath).create(recursive: true);
-  await file.writeAsString(new JsonEncoder.withIndent('  ').convert(durations));
+  await file.writeAsString(const JsonEncoder.withIndent('  ').convert(durations));
 }
 
 void main() {
@@ -176,6 +176,6 @@ void main() {
       await summary.writeSummaryToFile('transitions', pretty: true);
       String histogramPath = path.join(testOutputsDirectory, 'transition_durations.timeline.json');
       await saveDurationsHistogram(timeline.json['traceEvents'], histogramPath);
-    }, timeout: new Timeout(new Duration(minutes: 5)));
+    }, timeout: const Timeout(const Duration(minutes: 5)));
   });
 }

examples/layers/raw/canvas.dart

@@ -42,7 +42,7 @@ ui.Picture paint(ui.Rect paintBounds) {
   canvas.rotate(math.PI/4.0);
 
   ui.Gradient yellowBlue = new ui.Gradient.linear(
-    <ui.Point>[new ui.Point(-radius, -radius), new ui.Point(0.0, 0.0)],
+    <ui.Point>[new ui.Point(-radius, -radius), const ui.Point(0.0, 0.0)],
     <ui.Color>[const ui.Color(0xFFFFFF00), const ui.Color(0xFF0000FF)]
   );
   canvas.drawRect(new ui.Rect.fromLTRB(-radius, -radius, radius, radius),
@@ -61,7 +61,7 @@ ui.Picture paint(ui.Rect paintBounds) {
   canvas.restore();
 
   paint.color = const ui.Color.fromARGB(128, 255, 0, 0);
-  canvas.drawCircle(new ui.Point(150.0, 300.0), radius, paint);
+  canvas.drawCircle(const ui.Point(150.0, 300.0), radius, paint);
 
   // When we're done issuing painting commands, we end the recording an receive
   // a Picture, which is an immutable record of the commands we've issued. You

examples/layers/rendering/flex_layout.dart

@@ -15,25 +15,25 @@ void main() {
   void addAlignmentRow(CrossAxisAlignment crossAxisAlignment) {
     TextStyle style = const TextStyle(color: const Color(0xFF000000));
     RenderParagraph paragraph = new RenderParagraph(new TextSpan(style: style, text: '$crossAxisAlignment'));
-    table.add(new RenderPadding(child: paragraph, padding: new EdgeInsets.only(top: 20.0)));
+    table.add(new RenderPadding(child: paragraph, padding: const EdgeInsets.only(top: 20.0)));
     RenderFlex row = new RenderFlex(crossAxisAlignment: crossAxisAlignment, textBaseline: TextBaseline.alphabetic);
-    style = new TextStyle(fontSize: 15.0, color: const Color(0xFF000000));
+    style = const TextStyle(fontSize: 15.0, color: const Color(0xFF000000));
     row.add(new RenderDecoratedBox(
-      decoration: new BoxDecoration(backgroundColor: const Color(0x7FFFCCCC)),
+      decoration: const BoxDecoration(backgroundColor: const Color(0x7FFFCCCC)),
       child: new RenderParagraph(new TextSpan(style: style, text: 'foo foo foo'))
     ));
-    style = new TextStyle(fontSize: 10.0, color: const Color(0xFF000000));
+    style = const TextStyle(fontSize: 10.0, color: const Color(0xFF000000));
     row.add(new RenderDecoratedBox(
-      decoration: new BoxDecoration(backgroundColor: const Color(0x7FCCFFCC)),
+      decoration: const BoxDecoration(backgroundColor: const Color(0x7FCCFFCC)),
       child: new RenderParagraph(new TextSpan(style: style, text: 'foo foo foo'))
     ));
     RenderFlex subrow = new RenderFlex(crossAxisAlignment: crossAxisAlignment, textBaseline: TextBaseline.alphabetic);
-    style = new TextStyle(fontSize: 25.0, color: const Color(0xFF000000));
+    style = const TextStyle(fontSize: 25.0, color: const Color(0xFF000000));
     subrow.add(new RenderDecoratedBox(
-      decoration: new BoxDecoration(backgroundColor: const Color(0x7FCCCCFF)),
+      decoration: const BoxDecoration(backgroundColor: const Color(0x7FCCCCFF)),
       child: new RenderParagraph(new TextSpan(style: style, text: 'foo foo foo foo'))
     ));
-    subrow.add(new RenderSolidColorBox(const Color(0x7FCCFFFF), desiredSize: new Size(30.0, 40.0)));
+    subrow.add(new RenderSolidColorBox(const Color(0x7FCCFFFF), desiredSize: const Size(30.0, 40.0)));
     row.add(subrow);
     table.add(row);
     final FlexParentData rowParentData = row.parentData;
@@ -49,11 +49,11 @@ void main() {
   void addJustificationRow(MainAxisAlignment justify) {
     const TextStyle style = const TextStyle(color: const Color(0xFF000000));
     RenderParagraph paragraph = new RenderParagraph(new TextSpan(style: style, text: '$justify'));
-    table.add(new RenderPadding(child: paragraph, padding: new EdgeInsets.only(top: 20.0)));
+    table.add(new RenderPadding(child: paragraph, padding: const EdgeInsets.only(top: 20.0)));
     RenderFlex row = new RenderFlex(direction: Axis.horizontal);
-    row.add(new RenderSolidColorBox(const Color(0xFFFFCCCC), desiredSize: new Size(80.0, 60.0)));
-    row.add(new RenderSolidColorBox(const Color(0xFFCCFFCC), desiredSize: new Size(64.0, 60.0)));
-    row.add(new RenderSolidColorBox(const Color(0xFFCCCCFF), desiredSize: new Size(160.0, 60.0)));
+    row.add(new RenderSolidColorBox(const Color(0xFFFFCCCC), desiredSize: const Size(80.0, 60.0)));
+    row.add(new RenderSolidColorBox(const Color(0xFFCCFFCC), desiredSize: const Size(64.0, 60.0)));
+    row.add(new RenderSolidColorBox(const Color(0xFFCCCCFF), desiredSize: const Size(160.0, 60.0)));
     row.mainAxisAlignment = justify;
     table.add(row);
     final FlexParentData rowParentData = row.parentData;
@@ -67,8 +67,8 @@ void main() {
   addJustificationRow(MainAxisAlignment.spaceAround);
 
   RenderDecoratedBox root = new RenderDecoratedBox(
-    decoration: new BoxDecoration(backgroundColor: const Color(0xFFFFFFFF)),
-    child: new RenderPadding(child: table, padding: new EdgeInsets.symmetric(vertical: 50.0))
+    decoration: const BoxDecoration(backgroundColor: const Color(0xFFFFFFFF)),
+    child: new RenderPadding(child: table, padding: const EdgeInsets.symmetric(vertical: 50.0))
   );
 
   new RenderingFlutterBinding(root: root);

examples/layers/rendering/hello_world.dart

@@ -16,7 +16,7 @@ void main() {
       alignment: FractionalOffset.center,
       // We use a RenderParagraph to display the text 'Hello, world.' without
       // any explicit styling.
-      child: new RenderParagraph(new TextSpan(text: 'Hello, world.'))
+      child: new RenderParagraph(const TextSpan(text: 'Hello, world.'))
     )
   );
 }

examples/layers/rendering/src/sector_layout.dart

@@ -572,7 +572,7 @@ class RenderSolidColor extends RenderDecoratedSector {
   @override
   void handleEvent(PointerEvent event, HitTestEntry entry) {
     if (event is PointerDownEvent) {
-      decoration = new BoxDecoration(backgroundColor: const Color(0xFFFF0000));
+      decoration = const BoxDecoration(backgroundColor: const Color(0xFFFF0000));
     } else if (event is PointerUpEvent) {
       decoration = new BoxDecoration(backgroundColor: backgroundColor);
     }

examples/layers/rendering/src/solid_color_box.dart

@@ -41,7 +41,7 @@ class RenderSolidColorBox extends RenderDecoratedBox {
   @override
   void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
     if (event is PointerDownEvent) {
-      decoration = new BoxDecoration(backgroundColor: const Color(0xFFFF0000));
+      decoration = const BoxDecoration(backgroundColor: const Color(0xFFFF0000));
     } else if (event is PointerUpEvent) {
       decoration = new BoxDecoration(backgroundColor: backgroundColor);
     }

examples/layers/widgets/custom_render_box.dart

@@ -28,9 +28,9 @@ class RenderDots extends RenderConstrainedBox {
   @override
   void paint(PaintingContext context, Offset offset) {
     final Canvas canvas = context.canvas;
-    canvas.drawRect(offset & size, new Paint()..color = new Color(0xFF0000FF));
+    canvas.drawRect(offset & size, new Paint()..color = const Color(0xFF0000FF));
 
-    Paint paint = new Paint()..color = new Color(0xFF00FF00);
+    Paint paint = new Paint()..color = const Color(0xFF00FF00);
     for (Point point in _dots.values)
       canvas.drawCircle(point, 50.0, paint);
 

examples/layers/widgets/gestures.dart

@@ -165,7 +165,7 @@ class _GestureDemoState extends State<GestureDemo> {
           left: 0.0,
           child: new Card(
             child: new Container(
-              padding: new EdgeInsets.all(4.0),
+              padding: const EdgeInsets.all(4.0),
               child: new Column(
                 children: <Widget>[
                   new Row(

examples/layers/widgets/sectors.dart

@@ -93,7 +93,7 @@ class SectorAppState extends State<SectorApp> {
     return new Column(
       children: <Widget>[
         new Container(
-          padding: new EdgeInsets.symmetric(horizontal: 8.0, vertical: 25.0),
+          padding: const EdgeInsets.symmetric(horizontal: 8.0, vertical: 25.0),
           child: new Row(
             children: <Widget>[
               new RaisedButton(
@@ -102,8 +102,8 @@ class SectorAppState extends State<SectorApp> {
                   child: new Row(
                     children: <Widget>[
                       new Container(
-                        padding: new EdgeInsets.all(4.0),
-                        margin: new EdgeInsets.only(right: 10.0),
+                        padding: const EdgeInsets.all(4.0),
+                        margin: const EdgeInsets.only(right: 10.0),
                         child: new WidgetToRenderBoxAdapter(renderBox: sectorAddIcon)
                       ),
                       new Text('ADD SECTOR'),
@@ -117,8 +117,8 @@ class SectorAppState extends State<SectorApp> {
                   child: new Row(
                     children: <Widget>[
                       new Container(
-                        padding: new EdgeInsets.all(4.0),
-                        margin: new EdgeInsets.only(right: 10.0),
+                        padding: const EdgeInsets.all(4.0),
+                        margin: const EdgeInsets.only(right: 10.0),
                         child: new WidgetToRenderBoxAdapter(renderBox: sectorRemoveIcon)
                       ),
                       new Text('REMOVE SECTOR'),
@@ -132,11 +132,11 @@ class SectorAppState extends State<SectorApp> {
         ),
         new Expanded(
           child: new Container(
-            margin: new EdgeInsets.all(8.0),
+            margin: const EdgeInsets.all(8.0),
             decoration: new BoxDecoration(
               border: new Border.all()
             ),
-            padding: new EdgeInsets.all(8.0),
+            padding: const EdgeInsets.all(8.0),
             child: new WidgetToRenderBoxAdapter(
               renderBox: sectors,
               onBuild: doUpdates

examples/layers/widgets/spinning_mixed.dart

@@ -44,8 +44,8 @@ void attachWidgetTreeToRenderTree(RenderProxyBox container) {
           new Rectangle(const Color(0xFF00FFFF)),
           new Material(
             child: new Container(
-              padding: new EdgeInsets.all(10.0),
-              margin: new EdgeInsets.all(10.0),
+              padding: const EdgeInsets.all(10.0),
+              margin: const EdgeInsets.all(10.0),
               child: new Row(
                 children: <Widget>[
                   new RaisedButton(
@@ -99,7 +99,7 @@ void main() {
   addFlexChildSolidColor(flexRoot, const Color(0xFF0000FF), flex: 1);
 
   transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity(), alignment: FractionalOffset.center);
-  RenderPadding root = new RenderPadding(padding: new EdgeInsets.all(80.0), child: transformBox);
+  RenderPadding root = new RenderPadding(padding: const EdgeInsets.all(80.0), child: transformBox);
 
   binding.renderView.child = root;
   binding.addPersistentFrameCallback(rotate);

examples/layers/widgets/styled_text.dart

@@ -46,7 +46,7 @@ Widget toStyledText(String name, String text) {
               style: _kUnderline,
               text: name
             ),
-            new TextSpan(text: ':')
+            const TextSpan(text: ':')
           ]
         ),
         new TextSpan(text: text)
@@ -108,7 +108,7 @@ class _StyledTextDemoState extends State<StyledTextDemo> {
     return new GestureDetector(
       onTap: _handleTap,
       child: new Container(
-        padding: new EdgeInsets.symmetric(horizontal: 8.0),
+        padding: const EdgeInsets.symmetric(horizontal: 8.0),
         child: new Column(
           children: children,
           mainAxisAlignment: MainAxisAlignment.center,

examples/stocks/lib/stock_data.dart

@@ -78,7 +78,7 @@ class StockDataFetcher {
         print("Failed to load stock data chunk ${_nextChunk - 1}");
         return null;
       }
-      JsonDecoder decoder = new JsonDecoder();
+      JsonDecoder decoder = const JsonDecoder();
       callback(new StockData(decoder.convert(json)));
       if (_nextChunk < _kChunkCount)
         _fetchNextChunk();

examples/stocks/lib/stock_symbol_viewer.dart

@@ -22,7 +22,7 @@ class _StockSymbolView extends StatelessWidget {
 
     TextStyle headings = Theme.of(context).textTheme.body2;
     return new Container(
-      padding: new EdgeInsets.all(20.0),
+      padding: const EdgeInsets.all(20.0),
       child: new Column(
         children: <Widget>[
           new Row(
@@ -47,11 +47,11 @@ class _StockSymbolView extends StatelessWidget {
           ),
           new RichText(
             text: new TextSpan(
-              style: DefaultTextStyle.of(context).style.merge(new TextStyle(fontSize: 8.0)),
+              style: DefaultTextStyle.of(context).style.merge(const TextStyle(fontSize: 8.0)),
               text: 'Prices may be delayed by ',
               children: <TextSpan>[
-                new TextSpan(text: 'several', style: new TextStyle(fontStyle: FontStyle.italic)),
-                new TextSpan(text: ' years.'),
+                const TextSpan(text: 'several', style: const TextStyle(fontStyle: FontStyle.italic)),
+                const TextSpan(text: ' years.'),
               ]
             )
           ),
@@ -75,7 +75,7 @@ class StockSymbolPage extends StatelessWidget {
       ),
       body: new SingleChildScrollView(
         child: new Container(
-          margin: new EdgeInsets.all(20.0),
+          margin: const EdgeInsets.all(20.0),
           child: new Card(
             child: new _StockSymbolView(
               stock: stock,
@@ -99,7 +99,7 @@ class StockSymbolBottomSheet extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return new Container(
-      padding: new EdgeInsets.all(10.0),
+      padding: const EdgeInsets.all(10.0),
       decoration: new BoxDecoration(
         border: new Border(top: new BorderSide(color: Colors.black26))
       ),

examples/stocks/test/icon_color_test.dart

@@ -59,7 +59,7 @@ void main() {
     // sanity check
     expect(find.text('MARKET'), findsOneWidget);
     expect(find.text('Account Balance'), findsNothing);
-    await tester.pump(new Duration(seconds: 2));
+    await tester.pump(const Duration(seconds: 2));
     expect(find.text('MARKET'), findsOneWidget);
     expect(find.text('Account Balance'), findsNothing);
 

examples/stocks/test_driver/scroll_perf_test.dart

@@ -28,14 +28,14 @@ void main() {
 
         // Scroll down
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, -300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, -300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
 
         // Scroll up
         for (int i = 0; i < 5; i++) {
-          await driver.scroll(stockList, 0.0, 300.0, new Duration(milliseconds: 300));
-          await new Future<Null>.delayed(new Duration(milliseconds: 500));
+          await driver.scroll(stockList, 0.0, 300.0, const Duration(milliseconds: 300));
+          await new Future<Null>.delayed(const Duration(milliseconds: 500));
         }
       });