Revert "Remove BottomNavigationBarItem.title deprecation" (flutter#91930)

Author: Piinks

packages/flutter/lib/src/cupertino/bottom_tab_bar.dart

@@ -254,6 +254,7 @@ class CupertinoTabBar extends StatelessWidget implements PreferredSizeWidget {
       Expanded(
         child: Center(child: active ? item.activeIcon : item.icon),
       ),
+      if (item.title != null) item.title!,
       if (item.label != null) Text(item.label!),
     ];
   }

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

@@ -185,8 +185,9 @@ class BottomNavigationBar extends StatefulWidget {
   }) : assert(items != null),
        assert(items.length >= 2),
        assert(
+        items.every((BottomNavigationBarItem item) => item.title != null) ||
         items.every((BottomNavigationBarItem item) => item.label != null),
-        'Every item must have a non-null label',
+        'Every item must have a non-null title or label',
        ),
        assert(0 <= currentIndex && currentIndex < items.length),
        assert(elevation == null || elevation >= 0.0),
@@ -246,13 +247,13 @@ class BottomNavigationBar extends StatefulWidget {
   final double iconSize;
 
   /// The color of the selected [BottomNavigationBarItem.icon] and
-  /// [BottomNavigationBarItem.label].
+  /// [BottomNavigationBarItem.title].
   ///
   /// If null then the [ThemeData.primaryColor] is used.
   final Color? selectedItemColor;
 
   /// The color of the unselected [BottomNavigationBarItem.icon] and
-  /// [BottomNavigationBarItem.label]s.
+  /// [BottomNavigationBarItem.title]s.
   ///
   /// If null then the [ThemeData.unselectedWidgetColor]'s color is used.
   final Color? unselectedItemColor;
@@ -691,7 +692,7 @@ class _Label extends StatelessWidget {
           ),
         ),
         alignment: Alignment.bottomCenter,
-        child: Text(item.label!),
+        child: item.title ?? Text(item.label!),
       ),
     );
 

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

@@ -78,13 +78,13 @@ class BottomNavigationBarThemeData with Diagnosticable {
   final IconThemeData? unselectedIconTheme;
 
   /// The color of the selected [BottomNavigationBarItem.icon] and
-  /// [BottomNavigationBarItem.label].
+  /// [BottomNavigationBarItem.title].
   ///
   /// See [BottomNavigationBar.selectedItemColor].
   final Color? selectedItemColor;
 
   /// The color of the unselected [BottomNavigationBarItem.icon] and
-  /// [BottomNavigationBarItem.label]s.
+  /// [BottomNavigationBarItem.title]s.
   ///
   /// See [BottomNavigationBar.unselectedItemColor].
   final Color? unselectedItemColor;

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

@@ -24,11 +24,17 @@ class BottomNavigationBarItem {
   /// The argument [icon] should not be null and the argument [label] should not be null when used in a Material Design's [BottomNavigationBar].
   const BottomNavigationBarItem({
     required this.icon,
+    @Deprecated(
+      'Use "label" instead, as it allows for an improved text-scaling experience. '
+      'This feature was deprecated after v1.19.0.',
+    )
+    this.title,
     this.label,
     Widget? activeIcon,
     this.backgroundColor,
     this.tooltip,
   }) : activeIcon = activeIcon ?? icon,
+       assert(label == null || title == null),
        assert(icon != null);
 
   /// The icon of the item.
@@ -61,6 +67,15 @@ class BottomNavigationBarItem {
   ///  * [BottomNavigationBarItem.icon], for a description of how to pair icons.
   final Widget activeIcon;
 
+  /// The title of the item. If the title is not provided only the icon will be shown when not used in a Material Design [BottomNavigationBar].
+  ///
+  /// This field is deprecated, use [label] instead.
+  @Deprecated(
+    'Use "label" instead, as it allows for an improved text-scaling experience. '
+    'This feature was deprecated after v1.19.0.',
+  )
+  final Widget? title;
+
   /// The text label for this [BottomNavigationBarItem].
   ///
   /// This will be used to create a [Text] widget to put in the bottom navigation bar.

packages/flutter/test/cupertino/bottom_tab_bar_test.dart

@@ -429,7 +429,7 @@ Future<void> main() async {
     semantics.dispose();
   });
 
-  testWidgets('Label of items should be nullable', (WidgetTester tester) async {
+  testWidgets('Title of items should be nullable', (WidgetTester tester) async {
     final MemoryImage iconProvider = MemoryImage(Uint8List.fromList(kTransparentImage));
     final List<int> itemsTapped = <int>[];