Native subclasses of a mixin include classes extending native classes

sdk/lib/_internal/compiler/implementation/js_backend/backend.dart

 // Copyright (c) 2012, 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.
 
 part of js_backend;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked;
 
   JavaScriptItemCompilationContext()
@@ skipping 434 matching lines @@
   }
 
   Set<ClassElement> nativeSubclassesOfMixin(ClassElement mixin) {
     Set<MixinApplicationElement> uses = compiler.world.mixinUses[mixin];
     if (uses == null) return null;
     Set<ClassElement> result = null;
     for (MixinApplicationElement use in uses) {
       Iterable<ClassElement> subclasses = compiler.world.subclassesOf(use);
       if (subclasses != null) {
         for (ClassElement subclass in subclasses) {
-          if (subclass.isNative()) {
+          if (Elements.isNativeOrExtendsNative(subclass)) {
             if (result == null) result = new Set<ClassElement>();
             result.add(subclass);
           }
         }
       }
     }
     return result;
   }
 
   bool operatorEqHandlesNullArgument(FunctionElement operatorEqfunction) {
@@ skipping 1138 matching lines @@
     copy(constant.values);
     copy(constant.protoValue);
     copy(constant);
   }
 
   void visitConstructed(ConstructedConstant constant) {
     copy(constant.fields);
     copy(constant);
   }
 }