Fix ClassElement.allSupertypes to include interfaces of mixins (issue 29767)

pkg/analyzer/test/src/dart/element/element_test.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 analyzer.test.src.dart.element.element_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 152 matching lines @@
     ClassElement classB = ElementFactory.classElement("B", classA.type);
     ClassElementImpl classC = ElementFactory.classElement2("C");
     InterfaceType typeObject = classA.supertype;
     InterfaceType typeA = classA.type;
     InterfaceType typeB = classB.type;
     InterfaceType typeC = classC.type;
     classC.mixins = <InterfaceType>[typeB];
     List<InterfaceType> supers = classC.allSupertypes;
     List<InterfaceType> types = new List<InterfaceType>();
     types.addAll(supers);
-    expect(types.contains(typeA), isFalse);
+    expect(types.contains(typeA), isTrue);
     expect(types.contains(typeB), isTrue);
     expect(types.contains(typeObject), isTrue);
     expect(types.contains(typeC), isFalse);
   }
 
   void test_getAllSupertypes_recursive() {
     ClassElementImpl classA = ElementFactory.classElement2("A");
     ClassElementImpl classB = ElementFactory.classElement("B", classA.type);
     classA.supertype = classB.type;
     List<InterfaceType> supers = classB.allSupertypes;
@@ skipping 4171 matching lines @@
 }
 
 class _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction
     extends InterfaceTypeImpl {
   _FunctionTypeImplTest_isSubtypeOf_baseCase_classFunction(ClassElement arg0)
       : super(arg0);
 
   @override
   bool get isDartCoreFunction => true;
 }