anchor.diff:  
     test_Annotation_local_constructor_named_param() async {
       addTestSource('''
  -class A { A({int one, String two: 'defaultValue'}) { } }
  +class A { const A({int one, String two: 'defaultValue'}); }
   @A(^) main() { }''');
       await computeSuggestions();
       assertSuggestArguments(namedArguments: ['one', 'two']);
  
positive.code:     addSource(
          '/libA.dart',
          '''
  library libA; class A { A({int one, String two: 'defaultValue'}) { } }''');
      addTestSource('import "/libA.dart"; @A(^) main() { }');
      await computeSuggestions();
      assertSuggestArguments(namedArguments: ['one', 'two']);
  
negative.code: 
    test_ArgumentList_imported_constructor_named_param2() async {
      //
      addSource('/libA.dart', 'library libA; class A{A.foo({int one}); }');
      addTestSource('import "/libA.dart"; main() { new A.foo(^);}');
      await computeSuggestions();
      assertSuggestArguments(namedArguments: ['one']);
  