Add warnings and hints to for-in.

pkg/compiler/lib/src/common/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.
 
 /// Library containing identifier, names, and selectors commonly used through
 /// the compiler.
 library dart2js.common.names;
 
 import '../elements/elements.dart' show
     Name,
     PublicName;
 import '../universe/universe.dart' show
     CallStructure,
     Selector;
 
 /// [String]s commonly used.
 class Identifiers {
   /// The name of the call operator.
   static const String call = 'call';
 
+  /// The name of the current element property used on iterators in for-each
+  /// loops.
+  static const String current = 'current';
+
   /// The name of the from environment constructors on 'int', 'bool' and
   /// 'String'.
   static const String fromEnvironment = 'fromEnvironment';
 
+  /// The name of the iterator property used in for-each loops.
+  static const String iterator = 'iterator';
+
   /// The name of the main method.
   static const String main = 'main';
 
   /// The name of the no such method handler on 'Object'.
   static const String noSuchMethod_ = 'noSuchMethod';
 
   /// The name of the runtime type property on 'Object'.
   static const String runtimeType_ = 'runtimeType';
 }
 
 /// [Name]s commonly used.
 class Names {
   /// The name of the call operator.
   static const Name call = const PublicName(Identifiers.call);
 
   /// The name of the current element property used on iterators in for-each
   /// loops.
-  static const Name current = const PublicName('current');
+  static const Name current = const PublicName(Identifiers.current);
 
   /// The name of the dynamic type.
   static const Name dynamic_ = const PublicName('dynamic');
 
   /// The name of the iterator property used in for-each loops.
-  static const Name iterator = const PublicName('iterator');
+  static const Name iterator = const PublicName(Identifiers.iterator);
 
   /// The name of the move next method used on iterators in for-each loops.
   static const Name moveNext = const PublicName('moveNext');
 
   /// The name of the no such method handler on 'Object'.
   static const Name noSuchMethod_ = const PublicName(Identifiers.noSuchMethod_);
 
   /// The name of the to-string method on 'Object'.
   static const Name toString_ = const PublicName('toString');
 }
@@ skipping 46 matching lines @@
   /// The URI for 'dart:mirrors'.
   static final Uri dart_mirrors = new Uri(scheme: 'dart', path: 'mirrors');
 
   /// The URI for 'dart:_internal'.
   static final Uri dart__internal = new Uri(scheme: 'dart', path: '_internal');
 
   /// The URI for 'dart:_native_typed_data'.
   static final Uri dart__native_typed_data =
       new Uri(scheme: 'dart', path: '_native_typed_data');
 }