anchor.diff:      return map;
     }
   
  -  ClassBuilder generateNativeClass(Class cls) {
  +  ClassBuilder createBuilderAndSetIsTrivial(Class cls) {
       ClassElement classElement = cls.element;
   
       // TODO(sra): Issue #13731- this is commented out as part of custom element
  
positive.code:     }
      builder.superName = superclass.name;
  
      bool hasFields = emitterTask.oldEmitter.classEmitter.emitFields(
          cls, builder, classIsNative: true);
      int propertyCount = builder.properties.length;
      emitterTask.oldEmitter.classEmitter.emitCheckedClassSetters(cls, builder);
      emitterTask.oldEmitter.classEmitter.emitInstanceMembers(
          classElement, builder);
      emitterTask.oldEmitter.classEmitter.emitCallStubs(cls, builder);
      emitterTask.oldEmitter.classEmitter
          .emitRuntimeTypeInformation(cls, builder);
  
      if (!hasFields &&
          builder.properties.length == propertyCount &&
          superclass is! MixinApplicationElement) {
        builder.isTrivial = true;
      }
  
      return builder;
    }
  
negative.code:     Map<Class, ClassBuilder> builders = new Map<Class, ClassBuilder>();
      for (Class cls in classes) {
        if (cls.isNative) {
          ClassBuilder builder = createBuilderAndSetIsTrivial(cls);
          builders[cls] = builder;
        }
      }
  