Fix error when choose noon on time picker (flutter#78478)

Author: Arkangel12

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

@@ -91,7 +91,7 @@ class TimeOfDay {
   DayPeriod get period => hour < hoursPerPeriod ? DayPeriod.am : DayPeriod.pm;
 
   /// Which hour of the current period (e.g., am or pm) this time is.
-  int get hourOfPeriod => hour - periodOffset;
+  int get hourOfPeriod => hour > hoursPerPeriod ? hour - periodOffset : hour;
 
   /// The hour at which the current period starts.
   int get periodOffset => period == DayPeriod.am ? 0 : hoursPerPeriod;

packages/flutter/test/material/time_test.dart

@@ -25,5 +25,24 @@ void main() {
       expect(await pumpTest(false), '7:00 AM');
       expect(await pumpTest(true), '07:00');
     });
+
+    testWidgets('return 12 hours at noon', (WidgetTester tester) async {
+      Future<String> pumpTest(bool alwaysUse24HourFormat) async {
+        late String formattedValue;
+        await tester.pumpWidget(MaterialApp(
+          home: MediaQuery(
+            data: MediaQueryData(alwaysUse24HourFormat: alwaysUse24HourFormat),
+            child: Builder(builder: (BuildContext context) {
+              formattedValue = const TimeOfDay(hour: 12, minute: 0).format(context);
+              return Container();
+            }),
+          ),
+        ));
+        return formattedValue;
+      }
+
+      expect(await pumpTest(false), '12:00 PM');
+      expect(await pumpTest(true), '12:00');
+    });
   });
 }