fix #30423, covariant parameter tearoff type should be Object

tests/language_strong/function_subtype_bound_closure4_test.dart

Index: tests/language_strong/function_subtype_bound_closure4_test.dart
diff --git a/tests/language_strong/function_subtype_bound_closure4_test.dart b/tests/language_strong/function_subtype_bound_closure4_test.dart
index 99cd7439e093b7110702d1c5da91c640cddcb15e..1b6bf7a9cde0cb6f37d74758cb3737123ceda056 100644
--- a/tests/language_strong/function_subtype_bound_closure4_test.dart
+++ b/tests/language_strong/function_subtype_bound_closure4_test.dart
@@ -16,15 +16,15 @@ class C<T> {
   void foo(T a, [String b]) {}
   void baz(T a, {String b}) {}
 
-  void test(String nameOfT, bool expectedResult) {
-    Expect.equals(expectedResult, foo is Foo, 'C<$nameOfT>.foo is Foo');
-    Expect.equals(expectedResult, foo is Bar, 'C<$nameOfT>.foo is Bar');
+  void test(String nameOfT) {
+    Expect.isTrue(foo is Foo, 'C<$nameOfT>.foo is not Foo');
+    Expect.isTrue(foo is Bar, 'C<$nameOfT>.foo is not Bar');
     Expect.isFalse(foo is Baz, 'C<$nameOfT>.foo is Baz');
     Expect.isFalse(foo is Boz, 'C<$nameOfT>.foo is Boz');
 
     Expect.isFalse(baz is Foo, 'C<$nameOfT>.baz is Foo');
     Expect.isFalse(baz is Bar, 'C<$nameOfT>.baz is Bar');
-    Expect.equals(expectedResult, baz is Baz, 'C<$nameOfT>.baz is Baz');
+    Expect.isTrue(baz is Baz, 'C<$nameOfT>.baz is not Baz');
     Expect.isFalse(baz is Boz, 'C<$nameOfT>.baz is Boz');
   }
 }
@@ -32,7 +32,7 @@ class C<T> {
 class D<S, T> extends C<T> {}
 
 main() {
-  new D<String, bool>().test('bool', true);
-  new D<bool, int>().test('int', false);
-  new D().test('dynamic', true);
+  new D<String, bool>().test('bool');
+  new D<bool, int>().test('int');
+  new D().test('dynamic');
 }