Revert "fix #30462, update function_type tests to understand covariant generics"

tests/language_2/function_type/function_type15_test.dart

Index: tests/language_2/function_type/function_type15_test.dart
diff --git a/tests/language_2/function_type/function_type15_test.dart b/tests/language_2/function_type/function_type15_test.dart
index 14367680959baad541643c0e50f36f5bc921528a..1067a9182a3ddf26a702f4a2eb4333c0767b8ed2 100644
--- a/tests/language_2/function_type/function_type15_test.dart
+++ b/tests/language_2/function_type/function_type15_test.dart
@@ -281,10 +281,10 @@ class U15<T> {
       });
     }
     if (tIsInt || tIsBool) {
-      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>);
+      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>);
     }
   }