Use ClassHierarchy.applyChanges() in MixinFullResolution.

pkg/kernel/test/class_hierarchy_test.dart

 // Copyright (c) 2017, 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.
 
 import 'package:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/src/incremental_class_hierarchy.dart';
 import 'package:kernel/testing/mock_sdk_program.dart';
 import 'package:kernel/text/ast_to_text.dart';
 import 'package:kernel/type_algebra.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(ClosedWorldClassHierarchyTest);
     defineReflectiveTests(IncrementalClassHierarchyTest);
   });
 }
 
 @reflectiveTest
 class ClosedWorldClassHierarchyTest extends _ClassHierarchyTest {
   ClassHierarchy createClassHierarchy(Program program) {
     return new ClosedWorldClassHierarchy(program);
   }
+
+  void test_applyChanges() {
+    var a = addClass(new Class(name: 'A', supertype: objectSuper));
+    addClass(new Class(name: 'B', supertype: a.asThisSupertype));
+
+    _assertTestLibraryText('''
+class A {}
+class B extends self::A {}
+''');
+
+    // No updated classes, the same hierarchy.
+    expect(hierarchy.applyChanges([]), same(hierarchy));
+
+    // Has updated classes, a new hierarchy.
+    var newHierarchy = hierarchy.applyChanges([a]);
+    expect(newHierarchy, isNot(same(hierarchy)));
+    expect(newHierarchy, new isInstanceOf<ClosedWorldClassHierarchy>());
+  }
 }
 
 @reflectiveTest
 class IncrementalClassHierarchyTest extends _ClassHierarchyTest {
   ClassHierarchy createClassHierarchy(Program program) {
     return new IncrementalClassHierarchy();
   }
+
+  void test_applyChanges() {
+    var a = addClass(new Class(name: 'A', supertype: objectSuper));
+    addClass(new Class(name: 'B', supertype: a.asThisSupertype));
+
+    _assertTestLibraryText('''
+class A {}
+class B extends self::A {}
+''');
+
+    // No updated classes, the same hierarchy.
+    expect(hierarchy.applyChanges([]), same(hierarchy));
+
+    // Has updated classes, a new hierarchy.
+    var newHierarchy = hierarchy.applyChanges([a]);
+    expect(newHierarchy, isNot(same(hierarchy)));
+    expect(newHierarchy, new isInstanceOf<IncrementalClassHierarchy>());
+  }
 }
 
 abstract class _ClassHierarchyTest {
   Program program;
   CoreTypes coreTypes;
 
   /// The test library.
   Library library;
 
   ClassHierarchy _hierarchy;
@@ skipping 857 matching lines @@
     actualText = actualText.replaceAll(' extends core::Object', '');
 
 //    if (actualText != expectedText) {
 //      print('-------- Actual --------');
 //      print(actualText + '------------------------');
 //    }
 
     expect(actualText, expectedText);
   }
 }