Add typedef AST node boilerplate.

pkg/kernel/test/type_parser.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.
 // A very simple parser for a subset of DartTypes for use in testing type
 // algebra.
 library kernel.test.type_parser;
 
 import 'package:kernel/kernel.dart';
 import 'package:kernel/text/ast_to_text.dart';
 
@@ skipping 123 matching lines @@
         scanToken();
         String name = this.tokenText;
         if (name == '_') return const BottomType();
         if (name == 'void') return const VoidType();
         if (name == 'dynamic') return const DynamicType();
         var target = lookupType(name);
         if (target == null) {
           return fail('Unresolved type $name');
         } else if (target is Class) {
           return new InterfaceType(target, parseOptionalTypeArgumentList());
+        } else if (target is Typedef) {
+          return new TypedefType(target, parseOptionalTypeArgumentList());
         } else if (target is TypeParameter) {
           if (peekToken() == Token.LeftAngle) {
             return fail('Attempt to apply type arguments to a type variable');
           }
           return new TypeParameterType(target);
         }
         return fail("Unexpected lookup result for $name: $target");
 
       case Token.LeftParen:
         List<DartType> parameters = <DartType>[];
@@ skipping 166 matching lines @@
 void main(List<String> args) {
   if (args.length != 1) {
     print('Usage: type_parser TYPE');
   }
   var environment = new LazyTypeEnvironment();
   var type = parseDartType(args[0], environment.lookup);
   var buffer = new StringBuffer();
   new Printer(buffer).writeType(type);
   print(buffer);
 }