fix #28630, instance method tear-offs are treated as strict arrows

pkg/analyzer/test/src/task/strong/checker_test.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.test.src.task.strong.checker_test;
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 import 'strong_test_helper.dart';
 
@@ skipping 3660 matching lines @@
 
   void test_superConstructor() {
     checkFile('''
 class A { A(A x) {} }
 class B extends A {
   B() : super(/*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/3);
 }
 ''');
   }
 
+  void test_tearOffTreatedConsistentlyAsStrictArrow() {
+    checkFile(r'''
+void foo(void f(String x)) {}
+
+class A {
+  Null bar1(dynamic x) => null;
+  void bar2(dynamic x) => null;
+  Null bar3(String x) => null;
+  void test() {
+    foo(bar1);
+    foo(bar2);
+    foo(bar3);
+  }
+}
+
+
+Null baz1(dynamic x) => null;
+void baz2(dynamic x) => null;
+Null baz3(String x) => null;
+void test() {
+  foo(baz1);
+  foo(baz2);
+  foo(baz3);
+}
+    ''');
+  }
+
   void test_ternaryOperator() {
     checkFile('''
 abstract class Comparable<T> {
   int compareTo(T other);
   static int compare(Comparable a, Comparable b) => a.compareTo(b);
 }
 typedef int Comparator<T>(T a, T b);
 
 typedef bool _Predicate<T>(T value);
 
@@ skipping 397 matching lines @@
     // Regression test for https://github.com/dart-lang/sdk/issues/25069
     checkFile('''
 typedef int Foo();
 void foo() {}
 void main () {
   Foo x = /*error:INVALID_ASSIGNMENT,info:USE_OF_VOID_RESULT*/foo();
 }
 ''');
   }
 }