anchor.diff:  
     @override
     void visitClassDeclaration(ClassDeclaration node) {
  +    var wasInGenericContext = inGenericContext;
  +    inGenericContext = inGenericContext || node.typeParameters != null;
       data.recordPercentage(
           'Classes with type parameters', node.typeParameters != null);
       var context = 'name';
  
positive.code:     }
      _recordTokenType('ClassDeclaration ($context)', node.implementsClause);
      super.visitClassTypeAlias(node);
    }
  
    @override
  
negative.code:           allowedKeywords: memberKeywords);
      }
      super.visitExtensionDeclaration(node);
      inGenericContext = wasInGenericContext;
    }
  
    @override
  