Revert "Remove deprecated Typematcher (#73751)"

This reverts commit fe00353.

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

@@ -258,6 +258,23 @@ class GlobalObjectKey<T extends State<StatefulWidget>> extends GlobalKey<T> {
   }
 }
 
+/// This class is a work-around for the "is" operator not accepting a variable value as its right operand.
+///
+/// This class is deprecated. It will be deleted soon.
+// TODO(a14n): Remove this when it goes to stable, https://github.com/flutter/flutter/pull/44189
+@Deprecated(
+  'TypeMatcher has been deprecated because it is no longer used in framework(only in deprecated methods). '
+  'This feature was deprecated after v1.12.1.'
+)
+@optionalTypeArgs
+class TypeMatcher<T> {
+  /// Creates a type matcher for the given type parameter.
+  const TypeMatcher();
+
+  /// Returns true if the given object is of type `T`.
+  bool check(dynamic object) => object is T;
+}
+
 /// Describes the configuration for an [Element].
 ///
 /// Widgets are the central class hierarchy in the Flutter framework. A widget