Re-land "fix #30462, update function_type tests to understand covariant generics"

tests/language_2/function_type/function_type21_test.dart

Index: tests/language_2/function_type/function_type21_test.dart
diff --git a/tests/language_2/function_type/function_type21_test.dart b/tests/language_2/function_type/function_type21_test.dart
index aaf396c7af59c53262ffcac1a2734bb6754dd31f..803299993c88c1f8214e5bbe38db6cd81687d420 100644
--- a/tests/language_2/function_type/function_type21_test.dart
+++ b/tests/language_2/function_type/function_type21_test.dart
@@ -247,10 +247,10 @@ class U21<T> {
       });
     }
     if (tIsInt || tIsBool) {
-      Expect.equals(tIsInt, m2 is F2<int>);
-      Expect.equals(tIsBool, m2 is F2<bool>);
-      Expect.equals(tIsInt, confuse(m2) is F2<int>);
-      Expect.equals(tIsBool, confuse(m2) is F2<bool>);
+      Expect.equals(true, m2 is F2<int>);
+      Expect.equals(true, m2 is F2<bool>);
+      Expect.equals(true, confuse(m2) is F2<int>);
+      Expect.equals(true, confuse(m2) is F2<bool>);
     }
   }