Support null locale before locale initialization, Roll engine to cdd592f5be97e824 (#23417)

cdd592f5b Reland 'Pass null instead of 'none' locale' (#6632)
2cd89200c Roll src/third_party/skia b1a002e850e1..327955b1ba19 (12 commits) (#6631)
edfe02481 13771 - iOS dictation bug (#6607)
cadf4405b Roll src/third_party/skia b9998cdceec7..b1a002e850e1 (13 commits) (#6626)

bin/internal/engine.version

-4c79e423dc6f89f98d8ceb263a5ca78e2f2da996
+cdd592f5be97e8245b31d7621bc95234b62c3a43

bin/internal/goldens.version

-2a4133039bc4f59613a73a6d871a7c0e6f2396fa
+afef1dc571f94a41751917d3946defba782335f7

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

@@ -678,14 +678,16 @@ class _WidgetsAppState extends State<WidgetsApp> implements WidgetsBindingObserv
   Locale _locale;
 
   Locale _resolveLocale(Locale newLocale, Iterable<Locale> supportedLocales) {
-    if (newLocale == null) {
-      return supportedLocales.first;
-    }
     if (widget.localeResolutionCallback != null) {
       final Locale locale = widget.localeResolutionCallback(newLocale, widget.supportedLocales);
       if (locale != null)
         return locale;
     }
+    // newLocale can be null when called before the platform has had a chance to
+    // initialize the locales. We default to the first supported locale.
+    if (newLocale == null) {
+      return supportedLocales.first;
+    }
 
     Locale matchesLanguageCode;
     for (Locale locale in supportedLocales) {

packages/flutter_localizations/test/widgets_test.dart

@@ -537,7 +537,7 @@ void main() {
       )
     );
 
-    // Startup time. Default test locale is const Locale('', ''), so
+    // Startup time. Default test locale is null, so
     // no supported matches. Use the first locale.
     await tester.pumpAndSettle();
     expect(find.text('zh_CN'), findsOneWidget);
@@ -581,9 +581,10 @@ void main() {
       )
     );
 
-    // Initial WidgetTester locale is new Locale('', '')
+    // Initial WidgetTester locale is null due to no platform intitializing it.
+    // The locale gets resolved to "en_US", which is the first supported locale.
     await tester.pumpAndSettle();
-    expect(find.text('_ TextDirection.ltr'), findsOneWidget);
+    expect(find.text('en_US TextDirection.ltr'), findsOneWidget);
 
     await tester.binding.setLocale('en', 'CA');
     await tester.pumpAndSettle();
@@ -622,9 +623,10 @@ void main() {
       )
     );
 
-    // Initial WidgetTester locale is new Locale('', '')
+    // Initial WidgetTester locale is null due to no platform intitializing it.
+    // The locale gets resolved to "en_US", which is the first supported locale.
     await tester.pumpAndSettle();
-    expect(find.text('_ TextDirection.rtl'), findsOneWidget);
+    expect(find.text('en_US TextDirection.rtl'), findsOneWidget);
 
     await tester.binding.setLocale('en', 'CA');
     await tester.pumpAndSettle();
@@ -655,9 +657,10 @@ void main() {
       )
     );
 
-    // Initial WidgetTester locale is new Locale('', '')
+    // Initial WidgetTester locale is null due to no platform intitializing it.
+    // The locale gets resolved to "en_US", which is the first supported locale.
     await tester.pumpAndSettle();
-    expect(find.text('_ TextDirection.rtl'), findsOneWidget);
+    expect(find.text('en_US TextDirection.rtl'), findsOneWidget);
 
     await tester.binding.setLocale('en', 'CA');
     await tester.pumpAndSettle();