anchor.diff:    }
   
     List buildSplitOffAliases() {
  +    if (backend.aliasedSuperMembers.isEmpty) return [];
       return [js(r'''
           var splitOffAliases = function(constructor) {
             var hasOwnProperty = Object.prototype.hasOwnProperty;
  
positive.code:         }
        }
      }''', [finishedClassesAccess,
             !nativeClasses.isEmpty,
             interceptorsByTagAccess,
             leafTagsAccess,
  
negative.code: 
          // Process aliased members due to super calls. We have to do this early
          // to ensure that we also hit the object class.
          if (#) splitOffAliases(constructor);
  
          // The superclass is only false (empty string) for the Dart Object
          // class.  The minifier together with noSuchMethod can put methods on
  