prefer const constructor (#8031)

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

@@ -232,7 +232,7 @@ class SnackBar extends StatelessWidget {
         child: new Semantics(
           container: true,
           child: new Dismissable(
-            key: new Key('dismissable'),
+            key: const Key('dismissable'),
             direction: DismissDirection.down,
             resizeDuration: null,
             onDismissed: (DismissDirection direction) {

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

@@ -135,7 +135,7 @@ typedef void GlobalKeyRemoveListener(GlobalKey key);
 
 /// A key that is unique across the entire app.
 ///
-/// Global keys uniquely indentify elements. Global keys provide access to other
+/// Global keys uniquely identify elements. Global keys provide access to other
 /// objects that are associated with elements, such as the a [BuildContext] and,
 /// for [StatefulWidget]s, a [State].
 ///

packages/flutter/test/material/drawer_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   testWidgets('Drawer control test', (WidgetTester tester) async {
-    final Key containerKey = new Key('container');
+    final Key containerKey = const Key('container');
 
     await tester.pumpWidget(
       new Scaffold(

packages/flutter/test/material/scaffold_test.dart

@@ -44,7 +44,7 @@ void main() {
   testWidgets('Floating action animation', (WidgetTester tester) async {
     await tester.pumpWidget(new Scaffold(
       floatingActionButton: new FloatingActionButton(
-        key: new Key("one"),
+        key: const Key('one'),
         onPressed: null,
         child: new Text("1")
       )
@@ -54,7 +54,7 @@ void main() {
 
     await tester.pumpWidget(new Scaffold(
       floatingActionButton: new FloatingActionButton(
-        key: new Key("two"),
+        key: const Key('two'),
         onPressed: null,
         child: new Text("2")
       )
@@ -68,7 +68,7 @@ void main() {
 
     await tester.pumpWidget(new Scaffold(
       floatingActionButton: new FloatingActionButton(
-        key: new Key("one"),
+        key: const Key('one'),
         onPressed: null,
         child: new Text("1")
       )

packages/flutter/test/material/snack_bar_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter/material.dart';
 void main() {
   testWidgets('SnackBar control test', (WidgetTester tester) async {
     String helloSnackBar = 'Hello SnackBar';
-    Key tapTarget = new Key('tap-target');
+    Key tapTarget = const Key('tap-target');
     await tester.pumpWidget(new MaterialApp(
       home: new Scaffold(
         body: new Builder(
@@ -53,7 +53,7 @@ void main() {
 
   testWidgets('SnackBar twice test', (WidgetTester tester) async {
     int snackBarCount = 0;
-    Key tapTarget = new Key('tap-target');
+    Key tapTarget = const Key('tap-target');
     await tester.pumpWidget(new MaterialApp(
       home: new Scaffold(
         body: new Builder(
@@ -128,7 +128,7 @@ void main() {
 
   testWidgets('SnackBar cancel test', (WidgetTester tester) async {
     int snackBarCount = 0;
-    Key tapTarget = new Key('tap-target');
+    Key tapTarget = const Key('tap-target');
     int time;
     ScaffoldFeatureController<SnackBar, SnackBarClosedReason> lastController;
     await tester.pumpWidget(new MaterialApp(
@@ -214,7 +214,7 @@ void main() {
 
   testWidgets('SnackBar dismiss test', (WidgetTester tester) async {
     int snackBarCount = 0;
-    Key tapTarget = new Key('tap-target');
+    Key tapTarget = const Key('tap-target');
     await tester.pumpWidget(new MaterialApp(
       home: new Scaffold(
         body: new Builder(

packages/flutter/test/material/tabs_test.dart

@@ -168,7 +168,7 @@ void main() {
 
   testWidgets('Scrollable TabBar tap centers selected tab', (WidgetTester tester) async {
     List<String> tabs = <String>['AAAAAA', 'BBBBBB', 'CCCCCC', 'DDDDDD', 'EEEEEE', 'FFFFFF', 'GGGGGG', 'HHHHHH', 'IIIIII', 'JJJJJJ', 'KKKKKK', 'LLLLLL'];
-    Key tabBarKey = new Key('TabBar');
+    Key tabBarKey = const Key('TabBar');
     await tester.pumpWidget(buildFrame(tabs: tabs, value: 'AAAAAA', isScrollable: true, tabBarKey: tabBarKey));
     TabController controller = DefaultTabController.of(tester.element(find.text('AAAAAA')));
     expect(controller, isNotNull);
@@ -189,7 +189,7 @@ void main() {
 
   testWidgets('TabBar can be scrolled independent of the selection', (WidgetTester tester) async {
     List<String> tabs = <String>['AAAA', 'BBBB', 'CCCC', 'DDDD', 'EEEE', 'FFFF', 'GGGG', 'HHHH', 'IIII', 'JJJJ', 'KKKK', 'LLLL'];
-    Key tabBarKey = new Key('TabBar');
+    Key tabBarKey = const Key('TabBar');
     await tester.pumpWidget(buildFrame(tabs: tabs, value: 'AAAA', isScrollable: true, tabBarKey: tabBarKey));
     TabController controller = DefaultTabController.of(tester.element(find.text('AAAA')));
     expect(controller, isNotNull);

packages/flutter/test/material/time_picker_test.dart

@@ -38,7 +38,7 @@ Future<Point> startPicker(WidgetTester tester, ValueChanged<TimeOfDay> onChanged
   await tester.pumpWidget(new _TimePickerLauncher(onChanged: onChanged));
   await tester.tap(find.text('X'));
   await tester.pumpUntilNoTransientCallbacks(const Duration(seconds: 1));
-  return tester.getCenter(find.byKey(new Key('time-picker-dial')));
+  return tester.getCenter(find.byKey(const Key('time-picker-dial')));
 }
 
 Future<Null> finishPicker(WidgetTester tester) async {

packages/flutter/test/material/user_accounts_drawer_header_test.dart

@@ -8,9 +8,9 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   testWidgets('UserAccountsDrawerHeader test', (WidgetTester tester) async {
-    final Key avatarA = new Key('A');
-    final Key avatarC = new Key('C');
-    final Key avatarD = new Key('D');
+    final Key avatarA = const Key('A');
+    final Key avatarC = const Key('C');
+    final Key avatarD = const Key('D');
 
     await tester.pumpWidget(
       new Material(
@@ -146,7 +146,7 @@ void main() {
     ));
     expect(find.text('A'), findsOneWidget);
 
-    final Key avatarA = new Key('A');
+    final Key avatarA = const Key('A');
     await tester.pumpWidget(buildFrame(
       currentAccountPicture: new CircleAvatar(key: avatarA, child: new Text('A')),
       accountName: new Text('accountName'),

packages/flutter/test/widgets/baseline_test.dart

@@ -10,7 +10,7 @@ void main() {
     await tester.pumpWidget(
       new Center(
         child: new DefaultTextStyle(
-          style: new TextStyle(
+          style: const TextStyle(
             fontFamily: 'Ahem',
             fontSize: 100.0,
           ),
@@ -28,7 +28,7 @@ void main() {
           baseline: 180.0,
           baselineType: TextBaseline.alphabetic,
           child: new DefaultTextStyle(
-            style: new TextStyle(
+            style: const TextStyle(
               fontFamily: 'Ahem',
               fontSize: 100.0,
             ),

packages/flutter/test/widgets/block_test.dart

@@ -6,7 +6,7 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 
-final Key blockKey = new Key('test');
+final Key blockKey = const Key('test');
 
 void main() {
   testWidgets('Cannot scroll a non-overflowing block', (WidgetTester tester) async {

packages/flutter/test/widgets/box_decoration_test.dart

@@ -23,7 +23,7 @@ void main() {
   });
 
   testWidgets('Bordered Container insets its child', (WidgetTester tester) async {
-    Key key = new Key('outerContainer');
+    Key key = const Key('outerContainer');
     await tester.pumpWidget(
       new Center(
         child: new Container(
@@ -42,7 +42,7 @@ void main() {
   testWidgets('BoxDecoration paints its border correctly', (WidgetTester tester) async {
     // Regression test for https://github.com/flutter/flutter/issues/7672
 
-    final Key key = new Key('Container with BoxDecoration');
+    final Key key = const Key('Container with BoxDecoration');
     Widget buildFrame(Border border) {
       return new Center(
         child: new Container(

packages/flutter/test/widgets/column_test.dart

@@ -8,10 +8,10 @@ import 'package:flutter/widgets.dart';
 
 void main() {
   testWidgets('Column with one flexible child', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // Default is MainAxisAlignment.start so children so the children's
@@ -54,10 +54,10 @@ void main() {
   });
 
   testWidgets('Column with default main axis parameters', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // Default is MainAxisAlignment.start so children so the children's
@@ -100,9 +100,9 @@ void main() {
   });
 
   testWidgets('Column with MainAxisAlignment.center', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // The 100x100 children's top edges should be at 200, 300
@@ -138,10 +138,10 @@ void main() {
   });
 
   testWidgets('Column with MainAxisAlignment.end', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // The 100x100 children's top edges should be at 300, 400, 500.
@@ -184,10 +184,10 @@ void main() {
   });
 
   testWidgets('Column with MainAxisAlignment.spaceBetween', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // The 100x100 children's top edges should be at 0, 250, 500
@@ -230,11 +230,11 @@ void main() {
   });
 
   testWidgets('Column with MainAxisAlignment.spaceAround', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
-    final Key child3Key = new Key('child3');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
+    final Key child3Key = const Key('child3');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // The 100x100 children's top edges should be at 25, 175, 325, 475
@@ -284,10 +284,10 @@ void main() {
   });
 
   testWidgets('Column with MainAxisAlignment.spaceEvenly', (WidgetTester tester) async {
-    final Key columnKey = new Key('column');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key columnKey = const Key('column');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     // The 100x20 children's top edges should be at 135, 290, 445
@@ -330,7 +330,7 @@ void main() {
   });
 
   testWidgets('Column and MainAxisSize.min', (WidgetTester tester) async {
-    final Key flexKey = new Key('flexKey');
+    final Key flexKey = const Key('flexKey');
 
     // Default is MainAxisSize.max so the Column should be as high as the test: 600.
     await tester.pumpWidget(new Center(
@@ -363,7 +363,7 @@ void main() {
   });
 
   testWidgets('Column MainAxisSize.min layout at zero size', (WidgetTester tester) async {
-    final Key childKey = new Key('childKey');
+    final Key childKey = const Key('childKey');
 
     await tester.pumpWidget(new Center(
       child: new Container(

packages/flutter/test/widgets/ensure_visible_test.dart

@@ -21,13 +21,13 @@ Widget buildSingleChildScrollView(Axis scrollDirection, { bool reverse: false })
         child: new BlockBody(
           mainAxis: scrollDirection,
           children: <Widget>[
-            new Container(key: new ValueKey<int>(0), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(1), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(2), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(3), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(4), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(5), width: 200.0, height: 200.0),
-            new Container(key: new ValueKey<int>(6), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(0), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(1), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(2), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(3), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(4), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(5), width: 200.0, height: 200.0),
+            new Container(key: const ValueKey<int>(6), width: 200.0, height: 200.0),
           ],
         ),
       ),
@@ -45,13 +45,13 @@ Widget buildListView(Axis scrollDirection, { bool reverse: false, bool shrinkWra
         reverse: reverse,
         shrinkWrap: shrinkWrap,
         children: <Widget>[
-          new Container(key: new ValueKey<int>(0), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(1), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(2), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(3), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(4), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(5), width: 200.0, height: 200.0),
-          new Container(key: new ValueKey<int>(6), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(0), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(1), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(2), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(3), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(4), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(5), width: 200.0, height: 200.0),
+          new Container(key: const ValueKey<int>(6), width: 200.0, height: 200.0),
         ],
       ),
     ),
@@ -189,7 +189,7 @@ void main() {
                       child: new Transform(
                         transform: new Matrix4.rotationZ(math.PI),
                         child: new Container(
-                          key: new ValueKey<int>(0),
+                          key: const ValueKey<int>(0),
                           width: 100.0,
                           height: 100.0,
                           decoration: const BoxDecoration(
@@ -391,7 +391,7 @@ void main() {
             viewportBuilder: (BuildContext context, ViewportOffset offset) {
               return new Viewport2(
                 offset: offset,
-                center: new ValueKey<int>(4),
+                center: const ValueKey<int>(4),
                 slivers: <Widget>[
                   buildSliver(0),
                   buildSliver(1),
@@ -441,7 +441,7 @@ void main() {
                     child: new Transform(
                       transform: new Matrix4.rotationZ(math.PI),
                       child: new Container(
-                        key: new ValueKey<int>(0),
+                        key: const ValueKey<int>(0),
                         width: 100.0,
                         height: 100.0,
                         decoration: const BoxDecoration(

packages/flutter/test/widgets/heroes_test.dart

@@ -5,9 +5,9 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 
-Key firstKey = new Key('first');
-Key secondKey = new Key('second');
-Key thirdKey = new Key('third');
+Key firstKey = const Key('first');
+Key secondKey = const Key('second');
+Key thirdKey = const Key('third');
 
 final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{
   '/': (BuildContext context) => new Material(

packages/flutter/test/widgets/hyperlink_test.dart

@@ -20,7 +20,7 @@ void main() {
         didTapRight = true;
       };
 
-    Key textKey = new Key('text');
+    Key textKey = const Key('text');
 
     await tester.pumpWidget(
       new Center(

packages/flutter/test/widgets/key_test.dart

@@ -47,11 +47,11 @@ void main() {
     expect(new ObjectKey(const Object()) == new ObjectKey(const Object()), isTrue); // ignore: prefer_const_constructors
     expect(new ObjectKey(new Object()) == new ObjectKey(new Object()), isFalse);
 
-    expect(new ValueKey<bool>(true), hasOneLineDescription);
+    expect(const ValueKey<bool>(true), hasOneLineDescription);
     expect(new UniqueKey(), hasOneLineDescription);
-    expect(new ObjectKey(true), hasOneLineDescription);
+    expect(const ObjectKey(true), hasOneLineDescription);
     expect(new GlobalKey(), hasOneLineDescription);
     expect(new GlobalKey(debugLabel: 'hello'), hasOneLineDescription);
-    expect(new GlobalObjectKey(true), hasOneLineDescription);
+    expect(const GlobalObjectKey(true), hasOneLineDescription);
   });
 }

packages/flutter/test/widgets/multichild_test.dart

@@ -61,7 +61,7 @@ void main() {
       new Stack(
         children: <Widget>[
           new DecoratedBox(decoration: kBoxDecorationA),
-          new DecoratedBox(key: new Key('b'), decoration: kBoxDecorationB),
+          new DecoratedBox(key: const Key('b'), decoration: kBoxDecorationB),
           new DecoratedBox(decoration: kBoxDecorationC),
         ]
       )
@@ -72,9 +72,9 @@ void main() {
     await tester.pumpWidget(
       new Stack(
         children: <Widget>[
-          new DecoratedBox(key: new Key('b'), decoration: kBoxDecorationB),
+          new DecoratedBox(key: const Key('b'), decoration: kBoxDecorationB),
           new DecoratedBox(decoration: kBoxDecorationC),
-          new DecoratedBox(key: new Key('a'), decoration: kBoxDecorationA),
+          new DecoratedBox(key: const Key('a'), decoration: kBoxDecorationA),
         ]
       )
     );
@@ -84,9 +84,9 @@ void main() {
     await tester.pumpWidget(
       new Stack(
         children: <Widget>[
-          new DecoratedBox(key: new Key('a'), decoration: kBoxDecorationA),
+          new DecoratedBox(key: const Key('a'), decoration: kBoxDecorationA),
           new DecoratedBox(decoration: kBoxDecorationC),
-          new DecoratedBox(key: new Key('b'), decoration: kBoxDecorationB),
+          new DecoratedBox(key: const Key('b'), decoration: kBoxDecorationB),
         ]
       )
     );
@@ -193,11 +193,11 @@ void main() {
       new Stack(
         children: <Widget>[
           new Container(
-            key: new Key('b'),
+            key: const Key('b'),
             child: new DecoratedBox(decoration: kBoxDecorationB)
           ),
           new Container(
-            key: new Key('a'),
+            key: const Key('a'),
             child: new DecoratedBox(decoration: kBoxDecorationA)
           ),
         ]
@@ -210,11 +210,11 @@ void main() {
       new Stack(
         children: <Widget>[
           new Container(
-            key: new Key('a'),
+            key: const Key('a'),
             child: new DecoratedBox(decoration: kBoxDecorationA)
           ),
           new Container(
-            key: new Key('b'),
+            key: const Key('b'),
             child: new DecoratedBox(decoration: kBoxDecorationB)
           ),
         ]
@@ -283,7 +283,7 @@ void main() {
       new Stack(
         children: <Widget>[
           new FlipWidget(
-            key: new Key('flip'),
+            key: const Key('flip'),
             left: new DecoratedBox(decoration: kBoxDecorationA),
             right: new DecoratedBox(decoration: kBoxDecorationB)
           ),
@@ -294,9 +294,9 @@ void main() {
     await tester.pumpWidget(
       new Stack(
         children: <Widget>[
-          new DecoratedBox(key: new Key('c'), decoration: kBoxDecorationC),
+          new DecoratedBox(key: const Key('c'), decoration: kBoxDecorationC),
           new FlipWidget(
-            key: new Key('flip'),
+            key: const Key('flip'),
             left: new DecoratedBox(decoration: kBoxDecorationA),
             right: new DecoratedBox(decoration: kBoxDecorationB)
           ),
@@ -315,11 +315,11 @@ void main() {
       new Stack(
         children: <Widget>[
           new FlipWidget(
-            key: new Key('flip'),
+            key: const Key('flip'),
             left: new DecoratedBox(decoration: kBoxDecorationA),
             right: new DecoratedBox(decoration: kBoxDecorationB)
           ),
-          new DecoratedBox(key: new Key('c'), decoration: kBoxDecorationC),
+          new DecoratedBox(key: const Key('c'), decoration: kBoxDecorationC),
         ]
       )
     );

packages/flutter/test/widgets/navigator_test.dart

@@ -162,7 +162,7 @@ void main() {
   });
 
   testWidgets('Navigator.of fails gracefully when not found in context', (WidgetTester tester) async {
-    Key targetKey = new Key('foo');
+    Key targetKey = const Key('foo');
     dynamic exception;
     Widget widget = new ThirdWidget(
       targetKey: targetKey,

packages/flutter/test/widgets/overscroll_indicator_test.dart

@@ -206,7 +206,7 @@ void main() {
               new Container(
                 width: 2000.0,
                 height: 2000.0,
-                decoration: new BoxDecoration(
+                decoration: const BoxDecoration(
                   backgroundColor: const Color(0xFF00FF00),
                 ),
               ),

packages/flutter/test/widgets/page_storage_test.dart

@@ -7,7 +7,7 @@ import 'package:flutter/material.dart';
 
 void main() {
   testWidgets('PageStorage read and write', (WidgetTester tester) async {
-    final Key builderKey = new Key('builderKey');
+    final Key builderKey = const Key('builderKey');
     StateSetter setState;
     int storedValue = 0;
 
@@ -56,7 +56,7 @@ void main() {
       );
     }
 
-    Key key = new Key('Key one');
+    Key key = const Key('Key one');
     await tester.pumpWidget(buildWidthKey(key));
     Element builderElement = tester.element(find.byKey(key));
     expect(PageStorage.of(builderElement), isNotNull);
@@ -65,7 +65,7 @@ void main() {
 
     // New StatefulBuilder widget - different key - but the same PageStorage identifier.
 
-    key = new Key('Key two');
+    key = const Key('Key two');
     await tester.pumpWidget(buildWidthKey(key));
     builderElement = tester.element(find.byKey(key));
     expect(PageStorage.of(builderElement), isNotNull);

packages/flutter/test/widgets/reparent_state_test.dart

@@ -199,7 +199,7 @@ void main() {
       itemExtent: 100.0,
       children: <Widget>[
         new Container(
-          key: new Key('container'),
+          key: const Key('container'),
           height: 100.0,
           child: new StateMarker(key: key),
         ),

packages/flutter/test/widgets/row_test.dart

@@ -8,10 +8,10 @@ import 'package:flutter/widgets.dart';
 
 void main() {
   testWidgets('Row with one Flexible child', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // Default is MainAxisAlignment.start so children so the children's
@@ -54,10 +54,10 @@ void main() {
   });
 
   testWidgets('Row with default main axis parameters', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // Default is MainAxisAlignment.start so children so the children's
@@ -100,9 +100,9 @@ void main() {
   });
 
   testWidgets('Row with MainAxisAlignment.center', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // The 100x100 children's left edges should be at 300, 400
@@ -138,10 +138,10 @@ void main() {
   });
 
   testWidgets('Row with MainAxisAlignment.end', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // The 100x100 children's left edges should be at 500, 600, 700.
@@ -184,10 +184,10 @@ void main() {
   });
 
   testWidgets('Row with MainAxisAlignment.spaceBetween', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // The 100x100 children's left edges should be at 0, 350, 700
@@ -230,11 +230,11 @@ void main() {
   });
 
   testWidgets('Row with MainAxisAlignment.spaceAround', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
-    final Key child3Key = new Key('child3');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
+    final Key child3Key = const Key('child3');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // The 100x100 children's left edges should be at 50, 250, 450, 650
@@ -284,10 +284,10 @@ void main() {
   });
 
   testWidgets('Row with MainAxisAlignment.spaceEvenly', (WidgetTester tester) async {
-    final Key rowKey = new Key('row');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
-    final Key child2Key = new Key('child2');
+    final Key rowKey = const Key('row');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
+    final Key child2Key = const Key('child2');
 
     // Default is MainAxisSize.max so the Row should be as wide as the test: 800.
     // The 200x100 children's left edges should be at 50, 300, 550
@@ -330,9 +330,9 @@ void main() {
   });
 
   testWidgets('Row and MainAxisSize.min', (WidgetTester tester) async {
-    final Key rowKey = new Key('rowKey');
-    final Key child0Key = new Key('child0');
-    final Key child1Key = new Key('child1');
+    final Key rowKey = const Key('rowKey');
+    final Key child0Key = const Key('child0');
+    final Key child1Key = const Key('child1');
 
     // Row with MainAxisSize.min without flexible children shrink wraps.
     // Row's width should be 250, children should be at 0, 100.
@@ -368,7 +368,7 @@ void main() {
   });
 
   testWidgets('Row MainAxisSize.min layout at zero size', (WidgetTester tester) async {
-    final Key childKey = new Key('childKey');
+    final Key childKey = const Key('childKey');
 
     await tester.pumpWidget(new Center(
       child: new Container(

packages/flutter/test/widgets/scroll_controller_test.dart

@@ -45,7 +45,7 @@ void main() {
     expect(realOffset(), equals(controller.offset));
 
     await tester.pumpWidget(new ListView(
-      key: new Key('second'),
+      key: const Key('second'),
       controller: controller,
       children: kStates.map<Widget>((String state) {
         return new Container(
@@ -66,7 +66,7 @@ void main() {
     ScrollController controller2 = new ScrollController();
 
     await tester.pumpWidget(new ListView(
-      key: new Key('second'),
+      key: const Key('second'),
       controller: controller2,
       children: kStates.map<Widget>((String state) {
         return new Container(
@@ -84,7 +84,7 @@ void main() {
     expect(() => controller.animateTo(132.0, duration: const Duration(milliseconds: 300), curve: Curves.ease), throws);
 
     await tester.pumpWidget(new ListView(
-      key: new Key('second'),
+      key: const Key('second'),
       controller: controller2,
       physics: const BouncingScrollPhysics(),
       children: kStates.map<Widget>((String state) {

packages/flutter/test/widgets/stack_test.dart

@@ -27,7 +27,7 @@ void main() {
   });
 
   testWidgets('Can change position data', (WidgetTester tester) async {
-    Key key = new Key('container');
+    Key key = const Key('container');
 
     await tester.pumpWidget(
       new Stack(
@@ -82,7 +82,7 @@ void main() {
   });
 
   testWidgets('Can remove parent data', (WidgetTester tester) async {
-    Key key = new Key('container');
+    Key key = const Key('container');
     Container container = new Container(key: key, width: 10.0, height: 10.0);
 
     await tester.pumpWidget(new Stack(children: <Widget>[ new Positioned(left: 10.0, child: container) ]));
@@ -110,8 +110,8 @@ void main() {
   });
 
   testWidgets('Can align non-positioned children', (WidgetTester tester) async {
-    Key child0Key = new Key('child0');
-    Key child1Key = new Key('child1');
+    Key child0Key = const Key('child0');
+    Key child1Key = const Key('child1');
 
     await tester.pumpWidget(
       new Center(
@@ -173,7 +173,7 @@ void main() {
   });
 
   testWidgets('Can hit test an IndexedStack', (WidgetTester tester) async {
-    Key key = new Key('indexedStack');
+    Key key = const Key('indexedStack');
     int itemCount = 3;
     List<int> itemsTapped;
 
@@ -197,7 +197,7 @@ void main() {
   });
 
   testWidgets('Can set width and height', (WidgetTester tester) async {
-    Key key = new Key('container');
+    Key key = const Key('container');
 
     BoxDecoration kBoxDecoration = const BoxDecoration(
       backgroundColor: const Color(0xFF00FF00)

packages/flutter/test/widgets/stateful_component_test.dart

@@ -58,7 +58,7 @@ void main() {
   testWidgets('Don\'t rebuild subwidgets', (WidgetTester tester) async {
     await tester.pumpWidget(
       new FlipWidget(
-        key: new Key('rebuild test'),
+        key: const Key('rebuild test'),
         left: new TestBuildCounter(),
         right: new DecoratedBox(decoration: kBoxDecorationB)
       )

packages/flutter/test/widgets/stateful_components_test.dart

@@ -45,8 +45,8 @@ class OuterContainerState extends State<OuterContainer> {
 
 void main() {
   testWidgets('resync stateful widget', (WidgetTester tester) async {
-    Key innerKey = new Key('inner');
-    Key outerKey = new Key('outer');
+    Key innerKey = const Key('inner');
+    Key outerKey = const Key('outer');
 
     InnerWidget inner1 = new InnerWidget(key: innerKey);
     InnerWidget inner2;