Specify types in generated closure args.

pkg/analysis_server/test/services/correction/fix_test.dart

 // Copyright (c) 2014, 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 'dart:async';
 
 import 'package:analysis_server/plugin/edit/fix/fix_core.dart';
 import 'package:analysis_server/plugin/edit/fix/fix_dart.dart';
 import 'package:analysis_server/protocol/protocol_generated.dart'
     hide AnalysisError;
@@ skipping 562 matching lines @@
 
   test_addMissingRequiredArg_cons_single_closure_4() async {
     _addMetaPackageSource();
 
     addSource(
         '/libA.dart',
         r'''
 library libA;
 import 'package:meta/meta.dart';
 
-typedef int Callback(a,b,c);
+typedef int Callback(int a, String b,c);

[Brian Wilkerson, 2017/05/04 18:04:58]

It would be good if we always added a space after a comma. Maybe in a future CL?

[pquitslund, 2017/05/04 19:53:58]

And actually we do!  This is the test source.  The generated code is below and
better spaced. :)

 
 class A {
   A({@required Callback callback}) {}
 }
 ''');
 
     await resolveTestUnit('''
 import 'libA.dart';
 
 main() {
   A a = new A();
 }
 ''');
     await assertHasFix(
         DartFixKind.ADD_MISSING_REQUIRED_ARGUMENT,
         '''
 import 'libA.dart';
 
 main() {
-  A a = new A(callback: (a, b, c) {});
+  A a = new A(callback: (int a, String b, c) {});
 }
 ''',
         target: '/test.dart');
   }
 
   test_addMissingRequiredArg_cons_single_list() async {
     _addMetaPackageSource();
 
     addSource(
         '/libA.dart',
@@ skipping 6275 matching lines @@
 
   @override
   final CompilationUnit unit;
 
   @override
   final AnalysisError error;
 
   _DartFixContextImpl(this.resourceProvider, this.getTopLevelDeclarations,
       this.analysisContext, this.astProvider, this.unit, this.error);
 }