Fix @protected access check from within defining class (#26614).

pkg/analyzer/test/generated/hint_code_test.dart

 // Copyright (c) 2016, 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.generated.hint_code_test;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source_io.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 1261 matching lines @@
   void b(int i) {
     a = i;
   }
 }
 ''');
     computeLibrarySourceErrors(source);
     assertNoErrors(source);
     verify([source]);
   }
 
+  void test_invalidUseOfProtectedMember_OK_setter_2() {
+    Source source = addSource(r'''
+import 'package:meta/meta.dart';
+class A {
+  int _a;
+  @protected
+  void set a(int a) { _a = a; }
+  A(int a) {
+    this.a = a;
+  }
+}
+''');
+    computeLibrarySourceErrors(source);
+    assertNoErrors(source);
+    verify([source]);
+  }
+
   void test_invalidUseOfProtectedMember_setter() {
     Source source = addSource(r'''
 import 'package:meta/meta.dart';
 class A {
   @protected
   void set a(int i) { }
 }
 class B{
   A a;
   b(int i) {
@@ skipping 2152 matching lines @@
   n() {
     var a = m(), b = m();
   }
 }''');
     computeLibrarySourceErrors(source);
     assertErrors(
         source, [HintCode.USE_OF_VOID_RESULT, HintCode.USE_OF_VOID_RESULT]);
     verify([source]);
   }
 }