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

tests/language_2/function_type/function_type50_test.dart

Index: tests/language_2/function_type/function_type50_test.dart
diff --git a/tests/language_2/function_type/function_type50_test.dart b/tests/language_2/function_type/function_type50_test.dart
index 79e132c7a8bc531b8b6cab8f0df603835e2140a3..e1b7cb33babd4bc2173f625dc2e7657ec8bace3d 100644
--- a/tests/language_2/function_type/function_type50_test.dart
+++ b/tests/language_2/function_type/function_type50_test.dart
@@ -221,10 +221,10 @@ class U50<T> {
       });
     }
     if (tIsInt || tIsBool) {
-      Expect.equals(tIsInt, m0 is F0<int>);
-      Expect.equals(tIsBool, m0 is F0<bool>);
-      Expect.equals(tIsInt, confuse(m0) is F0<int>);
-      Expect.equals(tIsBool, confuse(m0) is F0<bool>);
+      Expect.equals(true, m0 is F0<int>);
+      Expect.equals(true, m0 is F0<bool>);
+      Expect.equals(true, confuse(m0) is F0<int>);
+      Expect.equals(true, confuse(m0) is F0<bool>);
     }
   }