anchor.diff:  @reflectiveTest
   class KeywordContributorWithNnbdTest extends KeywordContributorTest {
     @override
  -  List<Keyword> get classBodyKeywords =>
  -      super.classBodyKeywords..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get constructorParameter =>
  -      super.constructorParameter..add(Keyword.REQUIRED);
  -
  -  @override
  -  List<Keyword> get declarationKeywords =>
  -      super.declarationKeywords..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get directiveAndDeclarationKeywords =>
  -      super.directiveAndDeclarationKeywords..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get directiveDeclarationAndLibraryKeywords =>
  -      super.directiveDeclarationAndLibraryKeywords..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get directiveDeclarationKeywords =>
  -      super.directiveDeclarationKeywords..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get methodParameter =>
  -      super.methodParameter..add(Keyword.REQUIRED);
  -
  -  @override
  -  List<Keyword> get statementStartInClass =>
  -      super.statementStartInClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInLoopInClass =>
  -      super.statementStartInLoopInClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInLoopOutsideClass =>
  -      super.statementStartInLoopOutsideClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInSwitchCaseInClass =>
  -      super.statementStartInSwitchCaseInClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInSwitchCaseOutsideClass =>
  -      super.statementStartInSwitchCaseOutsideClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInSwitchInClass =>
  -      super.statementStartInSwitchInClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartInSwitchOutsideClass =>
  -      super.statementStartInSwitchOutsideClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get statementStartOutsideClass =>
  -      super.statementStartOutsideClass..add(Keyword.LATE);
  -
  -  @override
  -  List<Keyword> get staticMember => super.staticMember..add(Keyword.LATE);
  -
  -  @override
     void setupResourceProvider() {
       super.setupResourceProvider();
       createAnalysisOptionsFile(experiments: [EnableString.non_nullable]);
  
positive.code:     return new KeywordContributor();
    }
  
    test_after_class_noPrefix() async {
      addTestSource('class A {} ^');
      await computeSuggestions();
  
negative.code: 
  import 'package:analysis_server/src/provisional/completion/dart/completion_dart.dart';
  import 'package:analysis_server/src/services/completion/dart/keyword_contributor.dart';
  import 'package:analyzer/dart/analysis/features.dart';
  import 'package:analyzer/dart/ast/token.dart';
  import 'package:analyzer/src/dart/analysis/experiments.dart';
  import 'package:analyzer_plugin/protocol/protocol_common.dart';
  