enable lints prefer_const_declarations and prefer_const_literals_to_create_immutables (#14848)

diff --git a/analysis_options.yaml b/analysis_options.yaml
index b202799..78a2e88 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -109,8 +109,8 @@
     - prefer_conditional_assignment
     - prefer_const_constructors
     - prefer_const_constructors_in_immutables
-    # - prefer_const_declarations # not yet tested
-    # - prefer_const_literals_to_create_immutables # not yet tested
+    - prefer_const_declarations
+    - prefer_const_literals_to_create_immutables
     # - prefer_constructors_over_static_methods # not yet tested
     - prefer_contains
     # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
diff --git a/analysis_options_repo.yaml b/analysis_options_repo.yaml
index fed4ed5..65ebfb7 100644
--- a/analysis_options_repo.yaml
+++ b/analysis_options_repo.yaml
@@ -102,8 +102,8 @@
     - prefer_conditional_assignment
     - prefer_const_constructors
     - prefer_const_constructors_in_immutables
-    # - prefer_const_declarations # not yet tested
-    # - prefer_const_literals_to_create_immutables # not yet tested
+    - prefer_const_declarations
+    - prefer_const_literals_to_create_immutables
     # - prefer_constructors_over_static_methods # not yet tested
     - prefer_contains
     # - prefer_expression_function_bodies # conflicts with https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#consider-using--for-short-functions-and-methods
diff --git a/packages/flutter/test/cupertino/dialog_test.dart b/packages/flutter/test/cupertino/dialog_test.dart
index 368ba56..53c8379 100644
--- a/packages/flutter/test/cupertino/dialog_test.dart
+++ b/packages/flutter/test/cupertino/dialog_test.dart
@@ -116,7 +116,7 @@
                       child: new CupertinoAlertDialog(
                         title: const Text('The Title'),
                         content: new Text('Very long content ' * 20),
-                        actions: <Widget>[
+                        actions: const <Widget>[
                           const CupertinoDialogAction(
                             child: const Text('Cancel'),
                           ),
diff --git a/packages/flutter/test/material/app_bar_test.dart b/packages/flutter/test/material/app_bar_test.dart
index 64783b5..a0c626e 100644
--- a/packages/flutter/test/material/app_bar_test.dart
+++ b/packages/flutter/test/material/app_bar_test.dart
@@ -10,7 +10,7 @@
 Widget buildSliverAppBarApp({ bool floating, bool pinned, double expandedHeight, bool snap: false }) {
   return new Localizations(
     locale: const Locale('en', 'US'),
-    delegates: <LocalizationsDelegate<dynamic>>[
+    delegates: const <LocalizationsDelegate<dynamic>>[
       DefaultMaterialLocalizations.delegate,
       DefaultWidgetsLocalizations.delegate,
     ],
diff --git a/packages/flutter/test/material/chip_test.dart b/packages/flutter/test/material/chip_test.dart
index c10e4d2..32de24a 100644
--- a/packages/flutter/test/material/chip_test.dart
+++ b/packages/flutter/test/material/chip_test.dart
@@ -241,7 +241,7 @@
     await tester.pumpWidget(
       new Localizations(
         locale: const Locale('en', 'US'),
-        delegates: <LocalizationsDelegate<dynamic>>[
+        delegates: const <LocalizationsDelegate<dynamic>>[
           DefaultWidgetsLocalizations.delegate,
           DefaultMaterialLocalizations.delegate,
         ],
@@ -256,7 +256,7 @@
     await tester.pumpWidget(
       new Localizations(
         locale: const Locale('en', 'US'),
-        delegates: <LocalizationsDelegate<dynamic>>[
+        delegates: const <LocalizationsDelegate<dynamic>>[
           DefaultWidgetsLocalizations.delegate,
           DefaultMaterialLocalizations.delegate,
         ],
@@ -428,7 +428,7 @@
     await tester.pumpWidget(
       new Localizations(
         locale: const Locale('en', 'US'),
-        delegates: <LocalizationsDelegate<dynamic>>[
+        delegates: const <LocalizationsDelegate<dynamic>>[
           DefaultWidgetsLocalizations.delegate,
           DefaultMaterialLocalizations.delegate,
         ],
@@ -468,7 +468,7 @@
     await tester.pumpWidget(
       new Localizations(
         locale: const Locale('en', 'US'),
-        delegates: <LocalizationsDelegate<dynamic>>[
+        delegates: const <LocalizationsDelegate<dynamic>>[
           DefaultWidgetsLocalizations.delegate,
           DefaultMaterialLocalizations.delegate,
         ],
diff --git a/packages/flutter/test/material/dialog_test.dart b/packages/flutter/test/material/dialog_test.dart
index 0c1f0f6..a8d08f6 100644
--- a/packages/flutter/test/material/dialog_test.dart
+++ b/packages/flutter/test/material/dialog_test.dart
@@ -236,7 +236,7 @@
 
     await tester.pumpWidget(new Localizations(
       locale: const Locale('en', 'US'),
-      delegates: <LocalizationsDelegate<dynamic>>[
+      delegates: const <LocalizationsDelegate<dynamic>>[
         DefaultWidgetsLocalizations.delegate,
         DefaultMaterialLocalizations.delegate,
       ],
diff --git a/packages/flutter/test/material/dropdown_test.dart b/packages/flutter/test/material/dropdown_test.dart
index 966da83..09132c1 100644
--- a/packages/flutter/test/material/dropdown_test.dart
+++ b/packages/flutter/test/material/dropdown_test.dart
@@ -65,7 +65,7 @@
   Widget build(BuildContext context) {
     return new Localizations(
       locale: const Locale('en', 'US'),
-      delegates: <LocalizationsDelegate<dynamic>>[
+      delegates: const <LocalizationsDelegate<dynamic>>[
         DefaultWidgetsLocalizations.delegate,
         DefaultMaterialLocalizations.delegate,
       ],
diff --git a/packages/flutter/test/material/modal_bottom_sheet_test.dart b/packages/flutter/test/material/modal_bottom_sheet_test.dart
index 0881a40..fb393a6 100644
--- a/packages/flutter/test/material/modal_bottom_sheet_test.dart
+++ b/packages/flutter/test/material/modal_bottom_sheet_test.dart
@@ -160,7 +160,7 @@
 
     await tester.pumpWidget(new Localizations(
       locale: const Locale('en', 'US'),
-      delegates: <LocalizationsDelegate<dynamic>>[
+      delegates: const <LocalizationsDelegate<dynamic>>[
         DefaultWidgetsLocalizations.delegate,
         DefaultMaterialLocalizations.delegate,
       ],
diff --git a/packages/flutter/test/material/popup_menu_test.dart b/packages/flutter/test/material/popup_menu_test.dart
index daedc4d..905ff04 100644
--- a/packages/flutter/test/material/popup_menu_test.dart
+++ b/packages/flutter/test/material/popup_menu_test.dart
@@ -442,7 +442,7 @@
   Widget build(BuildContext context) {
     return new Localizations(
       locale: const Locale('en', 'US'),
-      delegates: <LocalizationsDelegate<dynamic>>[
+      delegates: const <LocalizationsDelegate<dynamic>>[
         DefaultWidgetsLocalizations.delegate,
         DefaultMaterialLocalizations.delegate,
       ],
diff --git a/packages/flutter/test/material/scaffold_test.dart b/packages/flutter/test/material/scaffold_test.dart
index 13df2a7..72ea8f8 100644
--- a/packages/flutter/test/material/scaffold_test.dart
+++ b/packages/flutter/test/material/scaffold_test.dart
@@ -363,7 +363,7 @@
                 child: const Text('body'),
               ),
             ),
-            persistentFooterButtons: <Widget>[const Placeholder()],
+            persistentFooterButtons: const <Widget>[const Placeholder()],
           ),
         ),
       ),
@@ -1056,7 +1056,7 @@
 
     if (geometryListenable != null)
       geometryListenable.removeListener(onGeometryChanged);
-    
+
     geometryListenable = newListenable;
     geometryListenable.addListener(onGeometryChanged);
     cache = new GeometryCachePainter(geometryListenable);
diff --git a/packages/flutter/test/material/snack_bar_test.dart b/packages/flutter/test/material/snack_bar_test.dart
index b3fbe0c..da3dd43 100644
--- a/packages/flutter/test/material/snack_bar_test.dart
+++ b/packages/flutter/test/material/snack_bar_test.dart
@@ -360,7 +360,7 @@
         ),
         child: new Scaffold(
           bottomNavigationBar: new BottomNavigationBar(
-            items: <BottomNavigationBarItem>[
+            items: const <BottomNavigationBarItem>[
               const BottomNavigationBarItem(icon: const Icon(Icons.favorite), title: const Text('Animutation')),
               const BottomNavigationBarItem(icon: const Icon(Icons.block), title: const Text('Zombo.com')),
             ],
diff --git a/packages/flutter/test/material/tabs_test.dart b/packages/flutter/test/material/tabs_test.dart
index 89de8f2..316122c 100644
--- a/packages/flutter/test/material/tabs_test.dart
+++ b/packages/flutter/test/material/tabs_test.dart
@@ -17,7 +17,7 @@
 Widget boilerplate({ Widget child, TextDirection textDirection: TextDirection.ltr }) {
   return new Localizations(
     locale: const Locale('en', 'US'),
-    delegates: <LocalizationsDelegate<dynamic>>[
+    delegates: const <LocalizationsDelegate<dynamic>>[
       DefaultMaterialLocalizations.delegate,
       DefaultWidgetsLocalizations.delegate,
     ],
@@ -1661,7 +1661,7 @@
           alignment: Alignment.topLeft,
           child: new TabBar(
             controller: controller,
-            tabs: <Tab>[
+            tabs: const <Tab>[
               const Tab(text: 'LEFT'),
               const Tab(text: 'RIGHT'),
             ],
diff --git a/packages/flutter/test/material/time_picker_test.dart b/packages/flutter/test/material/time_picker_test.dart
index bd7cd2d..6ec59c1 100644
--- a/packages/flutter/test/material/time_picker_test.dart
+++ b/packages/flutter/test/material/time_picker_test.dart
@@ -229,7 +229,7 @@
     await tester.pumpWidget(
       new Localizations(
         locale: const Locale('en', 'US'),
-        delegates: <LocalizationsDelegate<dynamic>>[
+        delegates: const <LocalizationsDelegate<dynamic>>[
           DefaultMaterialLocalizations.delegate,
           DefaultWidgetsLocalizations.delegate,
         ],
diff --git a/packages/flutter/test/widgets/nested_scroll_view_test.dart b/packages/flutter/test/widgets/nested_scroll_view_test.dart
index 4b07098..b879116 100644
--- a/packages/flutter/test/widgets/nested_scroll_view_test.dart
+++ b/packages/flutter/test/widgets/nested_scroll_view_test.dart
@@ -25,7 +25,7 @@
 Widget buildTest({ ScrollController controller, String title:'TTTTTTTT' }) {
   return new Localizations(
     locale: const Locale('en', 'US'),
-    delegates: <LocalizationsDelegate<dynamic>>[
+    delegates: const <LocalizationsDelegate<dynamic>>[
       DefaultMaterialLocalizations.delegate,
       DefaultWidgetsLocalizations.delegate,
     ],
diff --git a/packages/flutter/test/widgets/parent_data_test.dart b/packages/flutter/test/widgets/parent_data_test.dart
index 418675e..04d3259 100644
--- a/packages/flutter/test/widgets/parent_data_test.dart
+++ b/packages/flutter/test/widgets/parent_data_test.dart
@@ -253,7 +253,7 @@
     await tester.pumpWidget(
       new Stack(
         textDirection: TextDirection.ltr,
-        children: <Widget>[
+        children: const <Widget>[
           const Positioned(
             top: 5.0,
             bottom: 8.0,
@@ -275,7 +275,7 @@
     await tester.pumpWidget(
       new Container(
         child: new Row(
-          children: <Widget>[
+          children: const <Widget>[
             const Positioned(
               top: 6.0,
               left: 7.0,
diff --git a/packages/flutter/test/widgets/semantics_test.dart b/packages/flutter/test/widgets/semantics_test.dart
index d6ad7cb..e43748d 100644
--- a/packages/flutter/test/widgets/semantics_test.dart
+++ b/packages/flutter/test/widgets/semantics_test.dart
@@ -913,7 +913,7 @@
             const Text('Label 1'),
             const Text('Label 2'),
             new Row(
-              children: <Widget>[
+              children: const <Widget>[
                 const Text('Label 3'),
                 const Text('Label 4'),
                 const Text('Label 5'),
@@ -976,7 +976,7 @@
             new Transform.rotate(
               angle: pi / 2.0,
               child: new Row(
-                children: <Widget>[
+                children: const <Widget>[
                   const Text('Label 3'),
                   const Text('Label 4'),
                   const Text('Label 5'),
diff --git a/packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart b/packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart
index d7d2932..7f03bf6 100644
--- a/packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart
+++ b/packages/flutter/test/widgets/slivers_appbar_floating_pinned_test.dart
@@ -15,7 +15,7 @@
           data: const MediaQueryData(),
           child: new CustomScrollView(
             controller: controller,
-            slivers: <Widget>[
+            slivers: const <Widget>[
               const SliverAppBar(floating: true, pinned: true, expandedHeight: 200.0, title: const Text('A')),
               const SliverAppBar(primary: false, pinned: true, title: const Text('B')),
               const SliverList(
diff --git a/packages/flutter/test/widgets/slivers_block_test.dart b/packages/flutter/test/widgets/slivers_block_test.dart
index 4a05643..5984c8b 100644
--- a/packages/flutter/test/widgets/slivers_block_test.dart
+++ b/packages/flutter/test/widgets/slivers_block_test.dart
@@ -14,7 +14,7 @@
       textDirection: TextDirection.ltr,
       child: new Viewport(
         offset: new ViewportOffset.fixed(offset),
-        slivers: <Widget>[
+        slivers: const <Widget>[
           const SliverList(
             delegate: const SliverChildListDelegate(const <Widget>[
               const SizedBox(height: 400.0, child: const Text('a')),
@@ -150,7 +150,7 @@
         textDirection: TextDirection.ltr,
         child: new Viewport(
           offset: offset,
-          slivers: <Widget>[
+          slivers: const <Widget>[
             const SliverList(
               delegate: const SliverChildListDelegate(const <Widget>[
                 const SizedBox(height: 251.0, child: const Text('a')),
@@ -261,7 +261,7 @@
         textDirection: TextDirection.ltr,
         child: new Viewport(
           offset: new ViewportOffset.zero(),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             const SliverList(
               delegate: const SliverChildListDelegate(const <Widget>[
                 const SizedBox(height: 400.0, child: const Text('a')),
@@ -279,7 +279,7 @@
         textDirection: TextDirection.ltr,
         child: new Viewport(
           offset: new ViewportOffset.fixed(100.0),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             const SliverList(
               delegate: const SliverChildListDelegate(const <Widget>[
                 const SizedBox(height: 400.0, child: const Text('a')),
@@ -297,7 +297,7 @@
         textDirection: TextDirection.ltr,
         child: new Viewport(
           offset: new ViewportOffset.fixed(100.0),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             const SliverList(
               delegate: const SliverChildListDelegate(const <Widget>[
                 const SizedBox(height: 4000.0, child: const Text('a')),
@@ -315,7 +315,7 @@
         textDirection: TextDirection.ltr,
         child: new Viewport(
           offset: new ViewportOffset.zero(),
-          slivers: <Widget>[
+          slivers: const <Widget>[
             const SliverList(
               delegate: const SliverChildListDelegate(const <Widget>[
                 const SizedBox(height: 4000.0, child: const Text('a')),
diff --git a/packages/flutter_localizations/test/date_time_test.dart b/packages/flutter_localizations/test/date_time_test.dart
index 4f282b1..00138e3 100644
--- a/packages/flutter_localizations/test/date_time_test.dart
+++ b/packages/flutter_localizations/test/date_time_test.dart
@@ -31,7 +31,7 @@
         await tester.pumpWidget(new MaterialApp(
           supportedLocales: <Locale>[locale],
           locale: locale,
-          localizationsDelegates: <LocalizationsDelegate<dynamic>>[
+          localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
             GlobalMaterialLocalizations.delegate,
           ],
           home: new Builder(builder: (BuildContext context) {
@@ -85,7 +85,7 @@
         await tester.pumpWidget(new MaterialApp(
           supportedLocales: <Locale>[locale],
           locale: locale,
-          localizationsDelegates: <LocalizationsDelegate<dynamic>>[
+          localizationsDelegates: const <LocalizationsDelegate<dynamic>>[
             GlobalMaterialLocalizations.delegate,
           ],
           home: new Builder(builder: (BuildContext context) {
diff --git a/packages/flutter_tools/lib/src/base/utils.dart b/packages/flutter_tools/lib/src/base/utils.dart
index 5d33997..cbbc5dd 100644
--- a/packages/flutter_tools/lib/src/base/utils.dart
+++ b/packages/flutter_tools/lib/src/base/utils.dart
@@ -15,7 +15,7 @@
 import 'file_system.dart';
 import 'platform.dart';
 
-final BotDetector _kBotDetector = const BotDetector();
+const BotDetector _kBotDetector = const BotDetector();
 
 class BotDetector {
   const BotDetector();