Store Typedef(s) in kernel when parsing with Fasta, deserilize in DillLibraryBuilder.

pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.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.
 
 library fasta.kernel_library_builder;
 
 import 'package:front_end/src/fasta/scanner/token.dart' show Token;
 
 import 'package:kernel/ast.dart';
 
@@ skipping 634 matching lines @@
 
   @override
   void buildBuilder(Builder builder, LibraryBuilder coreLibrary) {
     if (builder is SourceClassBuilder) {
       Class cls = builder.build(this, coreLibrary);
       library.addClass(cls);
     } else if (builder is KernelFieldBuilder) {
       library.addMember(builder.build(this)..isStatic = true);
     } else if (builder is KernelProcedureBuilder) {
       library.addMember(builder.build(this)..isStatic = true);
-    } else if (builder is FunctionTypeAliasBuilder) {
-      // Kernel discard typedefs and use their corresponding function types
-      // directly.
+    } else if (builder is KernelFunctionTypeAliasBuilder) {
+      library.addTypedef(builder.build(this));
     } else if (builder is KernelEnumBuilder) {
       library.addClass(builder.build(this, coreLibrary));
     } else if (builder is PrefixBuilder) {
       // Ignored. Kernel doesn't represent prefixes.
     } else if (builder is BuiltinTypeBuilder) {
       // Nothing needed.
     } else {
       internalError("Unhandled builder: ${builder.runtimeType}");
     }
   }
@@ skipping 180 matching lines @@
           mixinApplicationClasses.putIfAbsent(name, () => builder);
       if (existing != builder) {
         part.scope.local.remove(name);
       }
     });
     super.includePart(part);
     nativeMethods.addAll(part.nativeMethods);
     boundlessTypeVariables.addAll(part.boundlessTypeVariables);
   }
 }