fix #30423, covariant parameter tearoff type should be Object

tests/language_strong/covariant_subtyping_test.dart

Index: tests/language_strong/covariant_subtyping_test.dart
diff --git a/tests/language_strong/covariant_subtyping_test.dart b/tests/language_strong/covariant_subtyping_test.dart
index 552f0b54d5517983dc3328eeb2a39adaaa427e04..c17b23dc4ce1f63164ffb08877fbe9dc631b50d9 100644
--- a/tests/language_strong/covariant_subtyping_test.dart
+++ b/tests/language_strong/covariant_subtyping_test.dart
@@ -221,6 +221,32 @@ testCallMethod() {
   }, isTypeError);
 }
 
+class TearOff<T> {
+  method1(T t) => null; // needs check
+  method2(Function(T) takesT) => null;
+  method3(T Function() returnsT) => null; // needs check
+  method4(Function(Function(T)) takesTakesT) => null; // needs check
+  method5(Function(T Function()) takesReturnsT) => null;
+  method6(Function(T) Function() returnsTakesT) => null;
+  method7(T Function() Function() returnsReturnsT) => null; // needs check
+}
+
+testTearOffRuntimeType() {
+  expectRTTI(tearoff, type) => Expect.equals('${tearoff.runtimeType}', type,
+      'covariant params should reify with Object as their type');
+
+  TearOff<num> t = new TearOff<int>();
+  expectRTTI(t.method1, '(Object) -> dynamic');
+
+  expectRTTI(t.method2, '((int) -> dynamic) -> dynamic');
+  expectRTTI(t.method3, '(Object) -> dynamic');
+
+  expectRTTI(t.method4, '(Object) -> dynamic');
+  expectRTTI(t.method5, '((() -> int) -> dynamic) -> dynamic');
+  expectRTTI(t.method6, '(() -> (int) -> dynamic) -> dynamic');
+  expectRTTI(t.method7, '(Object) -> dynamic');
+}
+
 main() {
   testField();
   testPrivateFields();
@@ -232,4 +258,5 @@ main() {
   testMixinApplication();
   testGenericMethodBounds();
   testCallMethod();
+  testTearOffRuntimeType();
 }