fix _debugCheckOwnerBuildTargetExists; sync localizations and tests (#12245)

* Revert "When parts of the program are changed in a hot reload, but not executed during the reassemble, warn that a restart may be needed. (#12304)"

This reverts commit 90028813a89a3de8154144e6e0f1edbe90dc2e4f.

* fix _debugCheckOwnerBuildTargetExists; sync localizations and tests

* address comments

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

@@ -3272,29 +3272,28 @@ abstract class Element extends DiagnosticableTree implements BuildContext {
   @mustCallSuper
   void didChangeDependencies() {
     assert(_active); // otherwise markNeedsBuild is a no-op
-    _debugCheckOwnerBuildTargetExists('didChangeDependencies');
+    assert(_debugCheckOwnerBuildTargetExists('didChangeDependencies'));
     markNeedsBuild();
   }
 
-  void _debugCheckOwnerBuildTargetExists(String methodName) {
+  bool _debugCheckOwnerBuildTargetExists(String methodName) {
     assert(() {
       if (owner._debugCurrentBuildTarget == null) {
         throw new FlutterError(
-          '$methodName for ${widget.runtimeType} was called at an '
-          'inappropriate time.\n'
-          '\n'
-          'It may only be called while the widgets are being built. A possible '
-          'cause of this error is when $methodName is called during '
-          'one of:\n'
-          '\n'
-          ' * network I/O event\n'
-          ' * file I/O event\n'
-          ' * timer\n'
-          ' * microtask (caused by Future.then, async/await, scheduleMicrotask)'
+            '$methodName for ${widget.runtimeType} was called at an '
+                'inappropriate time.\n'
+                'It may only be called while the widgets are being built. A possible '
+                'cause of this error is when $methodName is called during '
+                'one of:\n'
+                ' * network I/O event\n'
+                ' * file I/O event\n'
+                ' * timer\n'
+                ' * microtask (caused by Future.then, async/await, scheduleMicrotask)'
         );
       }
       return true;
-    });
+    }());
+    return true;
   }
 
   /// Returns a description of what caused this element to be created.
@@ -3942,7 +3941,7 @@ class InheritedElement extends ProxyElement {
   /// by first obtaining their [InheritedElement] using
   /// [BuildContext.ancestorInheritedElementForWidgetOfExactType].
   void dispatchDidChangeDependencies() {
-    _debugCheckOwnerBuildTargetExists('dispatchDidChangeDependencies');
+    assert(_debugCheckOwnerBuildTargetExists('dispatchDidChangeDependencies'));
     for (Element dependent in _dependents) {
       assert(() {
         // check that it really is our descendant

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

@@ -206,23 +206,20 @@ class _LocalizationsScope extends InheritedWidget {
     Key key,
     @required this.locale,
     @required this.localizationsState,
-    @required this.loadGeneration,
+    @required this.typeToResources,
     Widget child,
   }) : super(key: key, child: child) {
     assert(localizationsState != null);
+    assert(typeToResources != null);
   }
 
   final Locale locale;
   final _LocalizationsState localizationsState;
-
-  /// A monotonically increasing number that changes after localizations
-  /// delegates have finished loading new data. When this number changes, it
-  /// triggers inherited widget notifications.
-  final int loadGeneration;
+  final Map<Type, dynamic> typeToResources;
 
   @override
   bool updateShouldNotify(_LocalizationsScope old) {
-    return loadGeneration != old.loadGeneration;
+    return typeToResources != old.typeToResources;
   }
 }
 
@@ -445,11 +442,6 @@ class _LocalizationsState extends State<Localizations> {
   final GlobalKey _localizedResourcesScopeKey = new GlobalKey();
   Map<Type, dynamic> _typeToResources = <Type, dynamic>{};
 
-  /// A monotonically increasing number that increases after localizations
-  /// delegates have finished loading new data, triggering inherited widget
-  /// notifications.
-  int _loadGeneration = 0;
-
   Locale get locale => _locale;
   Locale _locale;
 
@@ -513,7 +505,6 @@ class _LocalizationsState extends State<Localizations> {
         setState(() {
           _typeToResources = value;
           _locale = locale;
-          _loadGeneration += 1;
         });
       });
     }
@@ -539,7 +530,7 @@ class _LocalizationsState extends State<Localizations> {
       key: _localizedResourcesScopeKey,
       locale: _locale,
       localizationsState: this,
-      loadGeneration: _loadGeneration,
+      typeToResources: _typeToResources,
       child: new Directionality(
         textDirection: _textDirection,
         child: widget.child,

packages/flutter/test/widgets/localizations_test.dart

@@ -159,6 +159,23 @@ Widget buildFrame({
   );
 }
 
+class SyncLoadTest extends StatefulWidget {
+  const SyncLoadTest();
+
+  @override
+  SyncLoadTestState createState() => new SyncLoadTestState();
+}
+
+class SyncLoadTestState extends State<SyncLoadTest> {
+  @override
+  Widget build(BuildContext context) {
+    return new Text(
+      TestLocalizations.of(context).message,
+      textDirection: TextDirection.rtl,
+    );
+  }
+}
+
 void main() {
   testWidgets('Localizations.localeFor in a WidgetsApp with system locale', (WidgetTester tester) async {
     BuildContext pageContext;
@@ -205,27 +222,27 @@ void main() {
   });
 
   testWidgets('Synchronously loaded localizations in a WidgetsApp', (WidgetTester tester) async {
-    BuildContext pageContext;
-    await tester.pumpWidget(
-      buildFrame(
-        delegates: <LocalizationsDelegate<dynamic>>[
-          new SyncTestLocalizationsDelegate()
-        ],
-        buildContent: (BuildContext context) {
-          pageContext = context;
-          return new Text(TestLocalizations.of(context).message);
-        }
-      )
-    );
+    final List<LocalizationsDelegate<dynamic>> delegates = <LocalizationsDelegate<dynamic>>[
+      new SyncTestLocalizationsDelegate(),
+      const DefaultWidgetsLocalizationsDelegate(),
+    ];
 
-    expect(TestLocalizations.of(pageContext), isNotNull);
+    Future<Null> pumpTest(Locale locale) async {
+      await tester.pumpWidget(new Localizations(
+        locale: locale,
+        delegates: delegates,
+        child: const SyncLoadTest(),
+      ));
+    }
+
+    await pumpTest(const Locale('en', 'US'));
     expect(find.text('en_US'), findsOneWidget);
 
-    await tester.binding.setLocale('en', 'GB');
+    await pumpTest(const Locale('en', 'GB'));
     await tester.pump();
     expect(find.text('en_GB'), findsOneWidget);
 
-    await tester.binding.setLocale('en', 'US');
+    await pumpTest(const Locale('en', 'US'));
     await tester.pump();
     expect(find.text('en_US'), findsOneWidget);
   });