Type annotations instead of closure comments.

lib/src/codegen/js_names.dart

 // Copyright (c) 2015, 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:collection';
 
 import '../js/js_ast.dart';
+import 'package:dev_compiler/src/options.dart';
 
 /// Unique instance for temporary variables. Will be renamed consistently
 /// across the entire file. Different instances will be named differently
 /// even if they have the same name, this makes it safe to use in code
 /// generation without needing global knowledge. See [JSNamer].
 ///
 // TODO(jmesserly): move into js_ast? add a boolean to Identifier?
 class TemporaryId extends Identifier {
   TemporaryId(String name) : super(name);
 }
@@ skipping 269 matching lines @@
 /// In particular, "caller" "callee" and "arguments" cannot be used.
 bool invalidStaticFieldName(String name) {
   switch (name) {
     case "arguments":
     case "caller":
     case "callee":
       return true;
   }
   return false;
 }
+
+/// We cannot destructure named params that clash with JS reserved names:
+/// see discussion in https://github.com/dart-lang/dev_compiler/issues/392.
+bool canDestructureNamedParams(Iterable<String> names, CodegenOptions options) {
+  return options.destructureNamedParams && !names.any(invalidVariableName);
+}