Fix current day not being decorated when it was disabled for picking. (#115240)

Fixes flutter/flutter#113277

Author: jgoyvaerts

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

@@ -979,16 +979,20 @@ class _DayPickerState extends State<_DayPicker> {
             color: selectedDayBackground,
             shape: BoxShape.circle,
           );
-        } else if (isDisabled) {
-          dayColor = disabledDayColor;
         } else if (isToday) {
-          // The current day gets a different text color and a circle stroke
+          // The current day gets a different text color (if enabled) and a circle stroke
           // border.
-          dayColor = todayColor;
+          if (isDisabled) {
+            dayColor = disabledDayColor;
+          } else {
+            dayColor = todayColor;
+          }
           decoration = BoxDecoration(
-            border: Border.all(color: todayColor),
+            border: Border.all(color: dayColor),
             shape: BoxShape.circle,
           );
+        } else if (isDisabled) {
+          dayColor = disabledDayColor;
         }
 
         Widget dayWidget = Container(

packages/flutter/test/material/calendar_date_picker_test.dart

@@ -337,6 +337,26 @@ void main() {
       );
     });
 
+    testWidgets('currentDate is highlighted even if it is disabled', (WidgetTester tester) async {
+      await tester.pumpWidget(calendarDatePicker(
+        firstDate: DateTime(2016, 1, 3),
+        lastDate: DateTime(2016, 1, 31),
+        currentDate: DateTime(2016, 1, 2), // not between first and last
+        initialDate: DateTime(2016, 1, 5),
+      ));
+      const Color disabledColor = Color(0x61000000); // default disabled color
+      expect(
+        Material.of(tester.element(find.text('2'))),
+        // The current day should be painted with a circle outline.
+        paints
+          ..circle(
+            color: disabledColor,
+            style: PaintingStyle.stroke,
+            strokeWidth: 1.0,
+          ),
+      );
+    });
+
     testWidgets('Selecting date does not switch picker to year selection', (WidgetTester tester) async {
       await tester.pumpWidget(calendarDatePicker(
         initialDate: DateTime(2020, DateTime.may, 10),