anchor.diff:    final ModularEmitter _emitter;
     final TypeEnvironmentStructure _environment;
     final TypeRecipe _recipe;
  +  final bool indexTypeVariablesOnDeclaringClass;
     final bool hackTypeVariablesToAny;
   
     final List<FunctionTypeVariable> functionTypeVariables = [];
  
positive.code:   int /*?*/ _indexIntoClassTypeVariables(TypeVariableType variable) {
      TypeVariableEntity element = variable.element;
      ClassEntity cls = element.typeDeclaration;
  
      // TODO(sra): We might be in a context where the class type variable has an
      // index, even though in the general case it is not at a specific index.
  
negative.code:       ]);
  
    jsAst.Literal _encodeSupertypeArgument(
            InterfaceType targetType, DartType supertypeArgument) =>
        _recipeEncoder.encodeDirectSupertypeRecipe(
            _emitter, targetType, supertypeArgument);
  }
  