Add optional FunctionType.positionalParameterNames and use them to resynthesize function-type forma…

pkg/kernel/lib/binary/ast_to_binary.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 kernel.ast_to_binary;
 
 import '../ast.dart';
 import '../import_table.dart';
 import 'tag.dart';
 import 'dart:convert';
 import 'dart:typed_data';
@@ skipping 1097 matching lines @@
       writeNodeList(node.typeArguments);
     }
   }
 
   visitFunctionType(FunctionType node) {
     if (node.requiredParameterCount == node.positionalParameters.length &&
         node.typeParameters.isEmpty &&
         node.namedParameters.isEmpty) {
       writeByte(Tag.SimpleFunctionType);
       writeNodeList(node.positionalParameters);
+      writeStringReferenceList(node.positionalParameterNames);
       writeNode(node.returnType);
     } else {
       writeByte(Tag.FunctionType);
       _typeParameterIndexer.enter(node.typeParameters);
       writeNodeList(node.typeParameters);
       writeUInt30(node.requiredParameterCount);
       writeUInt30(
           node.positionalParameters.length + node.namedParameters.length);
       writeNodeList(node.positionalParameters);
       writeNodeList(node.namedParameters);
+      writeStringReferenceList(node.positionalParameterNames);
       writeNode(node.returnType);
       _typeParameterIndexer.exit(node.typeParameters);
     }
   }
 
   visitNamedType(NamedType node) {
     writeStringReference(node.name);
     writeNode(node.type);
   }
 
@@ skipping 240 matching lines @@
     putOptional(node.documentationComment);
     super.visitConstructor(node);
   }
 
   @override
   visitField(Field node) {
     putOptional(node.documentationComment);
     super.visitField(node);
   }
 
+  @override
+  visitFunctionType(FunctionType node) {
+    node.positionalParameterNames.forEach(put);
+    super.visitFunctionType(node);
+  }
+
   visitNamedExpression(NamedExpression node) {
     put(node.name);
     node.visitChildren(this);
   }
 
   @override
   visitProcedure(Procedure node) {
     putOptional(node.documentationComment);
     super.visitProcedure(node);
   }
@@ skipping 138 matching lines @@
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     flushedLength += length;
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }