Gardening: Revert "fix #30423, covariant parameter tearoff type should be Object" (TBR)

tests/language_strong/function_subtype_cast1_test.dart

Index: tests/language_strong/function_subtype_cast1_test.dart
diff --git a/tests/language_strong/function_subtype_cast1_test.dart b/tests/language_strong/function_subtype_cast1_test.dart
index e23eb0fd8603fdaf741ef3a2499825989714b778..d2ff18088b85a8848f99000722c5df3d80a57fa4 100644
--- a/tests/language_strong/function_subtype_cast1_test.dart
+++ b/tests/language_strong/function_subtype_cast1_test.dart
@@ -21,12 +21,12 @@ void main() {
   Expect.isNotNull(new Class().bar as Bar);
 
   Expect.isNotNull(new Class<int>().bar as Foo);
-  Expect.isNotNull(new Class<int>().bar as Foo<bool>);
+  Expect.throws(() => new Class<int>().bar as Foo<bool>, (e) => true);
   Expect.isNotNull(new Class<int>().bar as Foo<int>);
   Expect.isNotNull(new Class<int>().bar as Bar);
 
   Expect.isNotNull(new Class<bool>().bar as Foo);
   Expect.isNotNull(new Class<bool>().bar as Foo<bool>);
-  Expect.isNotNull(new Class<bool>().bar as Foo<int>);
-  Expect.isNotNull(new Class<bool>().bar as Bar);
+  Expect.throws(() => new Class<bool>().bar as Foo<int>, (e) => true);
+  Expect.throws(() => new Class<bool>().bar as Bar, (e) => true);
 }