Find native classes with mixins in NativeClassFinder

pkg/compiler/lib/src/resolution/resolution_strategy.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.
 
 library dart2js.resolution_strategy;
 
 import '../common.dart';
 import '../common_elements.dart';
 import '../common/backend_api.dart';
 import '../common/names.dart';
@@ skipping 288 matching lines @@
       ClassElement cls, void f(ClassElement declarer, MemberElement member)) {
     cls.ensureResolved(_resolution);
     cls.forEachMember((ClassElement declarer, MemberElement member) {
       if (member.isSynthesized) return;
       if (member.isMalformed) return;
       f(declarer, member);
     }, includeSuperAndInjectedMembers: true);
   }
 
   @override
-  ClassEntity getSuperClass(ClassElement cls) {
+  ClassEntity getSuperClass(ClassElement cls,
+      {bool skipUnnamedMixinApplications: false}) {
     cls.ensureResolved(_resolution);
-    return cls.superclass;
+    ClassElement superclass = cls.superclass;
+    if (skipUnnamedMixinApplications) {
+      while (superclass != null && superclass.isUnnamedMixinApplication) {
+        superclass = superclass.superclass;
+      }
+    }
+    return superclass;
   }
 
   @override
   void forEachSupertype(
       ClassElement cls, void f(ResolutionInterfaceType supertype)) {
     cls.allSupertypes
         .forEach((ResolutionInterfaceType supertype) => f(supertype));
   }
 
   @override
@@ skipping 290 matching lines @@
             }
           }
         });
       });
     }
 
     _compiler.libraryLoader.libraries
         .forEach(processJsInteropAnnotationsInLibrary);
   }
 }