Find native classes with mixins in NativeClassFinder

pkg/compiler/lib/src/native/enqueue.dart

Index: pkg/compiler/lib/src/native/enqueue.dart
diff --git a/pkg/compiler/lib/src/native/enqueue.dart b/pkg/compiler/lib/src/native/enqueue.dart
index 8aea701e4282a11225a1d4ad84ba0d458e957ec6..4530ae522f4f2905b4cc7609a1a48de59e29b5e4 100644
--- a/pkg/compiler/lib/src/native/enqueue.dart
+++ b/pkg/compiler/lib/src/native/enqueue.dart
@@ -199,6 +199,10 @@ class NativeResolutionEnqueuer extends NativeEnqueuerBase {
       this._nativeClassFinder)
       : super(options, elementEnvironment, commonElements);
 
+  Iterable<ClassEntity> get nativeClassesForTesting => _nativeClasses;
+
+  Iterable<ClassEntity> get registeredClassesForTesting => _registeredClasses;
+
   void _registerBackendUse(FunctionEntity element) {
     _backendUsageBuilder.registerBackendFunctionUse(element);
     _backendUsageBuilder.registerGlobalFunctionDependency(element);