Use ClassHierarchy.applyChanges() in MixinFullResolution.

pkg/kernel/lib/class_hierarchy.dart

Index: pkg/kernel/lib/class_hierarchy.dart
diff --git a/pkg/kernel/lib/class_hierarchy.dart b/pkg/kernel/lib/class_hierarchy.dart
index c17bd8c11d07424108ab78050ccfb0801f790249..b0ce1064b22df6c8ec3b02f5b02199096dbde27e 100644
--- a/pkg/kernel/lib/class_hierarchy.dart
+++ b/pkg/kernel/lib/class_hierarchy.dart
@@ -120,10 +120,19 @@ abstract class ClassHierarchy {
   /// parameter determines which type of access is being overridden.
   void forEachOverridePair(Class class_,
       callback(Member declaredMember, Member interfaceMember, bool isSetter));
+
+  /// This method is invoked by the client after it changed the [changed]
+  /// classes, and some of the information that this hierarchy might have
+  /// cached, is not valid anymore. The hierarchy may perform required
+  /// updates and return the same instance, or return a new instance.
+  ClassHierarchy applyChanges(Iterable<Class> changed);

[ahe, 2017/06/08 20:18:10]

I suggest that you rename this parameter to classes.

Then you can write:

This method is invoked by the client after it changed [classes], ...

[scheglov, 2017/06/08 21:00:25]

Done.

 }
 
 /// Implementation of [ClassHierarchy] for closed world.
 class ClosedWorldClassHierarchy implements ClassHierarchy {
+  /// The [Program] that this class hierarchy represents.
+  final Program program;

[ahe, 2017/06/08 20:18:10]

Private?

[scheglov, 2017/06/08 21:00:24]

Done.

+
   /// All classes in the program.
   ///
   /// The list is ordered so that classes occur after their super classes.
@@ -447,7 +456,13 @@ class ClosedWorldClassHierarchy implements ClassHierarchy {
     return new ClassSet(this, _infoFor[class_].subclassIntervalList);
   }
 
-  ClosedWorldClassHierarchy._internal(Program program, int numberOfClasses)
+  @override
+  ClassHierarchy applyChanges(Iterable<Class> changed) {
+    if (changed.isEmpty) return this;
+    return new ClosedWorldClassHierarchy(program);
+  }
+
+  ClosedWorldClassHierarchy._internal(this.program, int numberOfClasses)
       : classes = new List<Class>(numberOfClasses) {
     // Build the class ordering based on a topological sort.
     for (var library in program.libraries) {