Provide access to list of types that cannot be subtyped (issue 23125)

pkg/analyzer/lib/src/generated/error_verifier.dart

 // Copyright (c) 2014, 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 engine.resolver.error_verifier;
 
 import "dart:math" as math;
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/static_type_analyzer.dart';
@@ skipping 252 matching lines @@
     this._hasExtUri = _currentLibrary.hasExtUri;
     _isEnclosingConstructorConst = false;
     _isInCatchClause = false;
     _isInStaticVariableDeclaration = false;
     _isInInstanceVariableDeclaration = false;
     _isInInstanceVariableInitializer = false;
     _isInConstructorInitializer = false;
     _isInStaticMethod = false;
     _boolType = _typeProvider.boolType;
     _intType = _typeProvider.intType;
-    _DISALLOWED_TYPES_TO_EXTEND_OR_IMPLEMENT = <InterfaceType>[
-      _typeProvider.nullType,
-      _typeProvider.numType,
-      _intType,
-      _typeProvider.doubleType,
-      _boolType,
-      _typeProvider.stringType
-    ];
+    _DISALLOWED_TYPES_TO_EXTEND_OR_IMPLEMENT = _typeProvider.nonSubtypableTypes;
   }
 
   @override
   Object visitAnnotation(Annotation node) {
     _checkForInvalidAnnotationFromDeferredLibrary(node);
     return super.visitAnnotation(node);
   }
 
   @override
   Object visitArgumentList(ArgumentList node) {
@@ skipping 5687 matching lines @@
     toCheck.add(type.element);
     // type arguments
     if (type is InterfaceType) {
       InterfaceType interfaceType = type;
       for (DartType typeArgument in interfaceType.typeArguments) {
         _addTypeToCheck(typeArgument);
       }
     }
   }
 }