Fix for parsing generic function types with Fasta.

pkg/analyzer/lib/src/dart/ast/ast_factory.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/ast_factory.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
 import 'package:front_end/src/scanner/token.dart';
 import 'package:meta/meta.dart';
@@ skipping 530 matching lines @@
           @required FormalParameterList parameters,
           Token question}) =>
       new FunctionTypedFormalParameterImpl(comment, metadata, covariantKeyword,
           returnType, identifier, typeParameters, parameters, question);
 
   @override
   GenericFunctionType genericFunctionType(
           TypeAnnotation returnType,
           Token functionKeyword,
           TypeParameterList typeParameters,
-          FormalParameterList _parameters) =>
+          FormalParameterList parameters) =>
       new GenericFunctionTypeImpl(
-          returnType, functionKeyword, typeParameters, _parameters);
+          returnType, functionKeyword, typeParameters, parameters);
 
   @override
   GenericTypeAlias genericTypeAlias(
           Comment comment,
           List<Annotation> metadata,
           Token typedefKeyword,
           SimpleIdentifier name,
           TypeParameterList typeParameters,
           Token equals,
           GenericFunctionType functionType,
@@ skipping 397 matching lines @@
 
   @override
   WithClause withClause(Token withKeyword, List<TypeName> mixinTypes) =>
       new WithClauseImpl(withKeyword, mixinTypes);
 
   @override
   YieldStatement yieldStatement(Token yieldKeyword, Token star,
           Expression expression, Token semicolon) =>
       new YieldStatementImpl(yieldKeyword, star, expression, semicolon);
 }