anchor.diff:      builder.addProperty(setterName,
           js.fun(args,
               js('$receiver.$fieldName = #', js(helperName)(arguments))));
  +    generateReflectionDataForFieldGetterOrSetter(
  +        member, setterName, builder, isGetter: false);
     }
   
     void emitClassConstructor(ClassElement classElement, ClassBuilder builder) {
  
positive.code:         : ['v'];
      builder.addProperty(setterName,
          js.fun(args, js('$receiver.$fieldName = v')));
    }
  
    bool canGenerateCheckedSetter(VariableElement field) {
  
negative.code:         : [];
      builder.addProperty(getterName,
          js.fun(args, js.return_(js('$receiver.$fieldName'))));
      generateReflectionDataForFieldGetterOrSetter(
          member, getterName, builder, isGetter: true);
    }
  
    void generateSetter(Element member, String fieldName, String accessorName,
  