Mark `IconData` `final` and `@mustBeConst`

packages/flutter/lib/foundation.dart

diff --git a/packages/flutter/lib/foundation.dart b/packages/flutter/lib/foundation.dart
index 5f774a2..df87090 100644
--- a/packages/flutter/lib/foundation.dart
+++ b/packages/flutter/lib/foundation.dart
@@ -14,6 +14,8 @@
         factory,
         immutable,
         internal,
+        // ignore: experimental_member_use
+        mustBeConst,
         mustCallSuper,
         nonVirtual,
         optionalTypeArgs,

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

diff --git a/packages/flutter/lib/src/widgets/icon_data.dart b/packages/flutter/lib/src/widgets/icon_data.dart
index 07b9892..341d4f9 100644
--- a/packages/flutter/lib/src/widgets/icon_data.dart
+++ b/packages/flutter/lib/src/widgets/icon_data.dart
@@ -20,7 +20,7 @@
 /// the code points (or instances of [IconData]) which are not referenced from
 /// Dart app code. See the [staticIconProvider] annotation for more details.
 @immutable
-class IconData {
+final class IconData {
   /// Creates icon data.
   ///
   /// Rarely used directly. Instead, consider using one of the predefined icons
@@ -45,9 +45,12 @@
   /// need to be explicitly opted out at build time). See [staticIconProvider]
   /// for more context.
   const IconData(
-    this.codePoint, {
-    this.fontFamily,
-    this.fontPackage,
+    // ignore: experimental_member_use
+    @mustBeConst this.codePoint, {
+    // ignore: experimental_member_use
+    @mustBeConst this.fontFamily,
+    // ignore: experimental_member_use
+    @mustBeConst this.fontPackage,
     this.matchTextDirection = false,
     this.fontFamilyFallback,
   });