Attempt to fix build.

pkg/intl/lib/extract_messages.dart

Index: pkg/intl/lib/extract_messages.dart
diff --git a/pkg/intl/lib/extract_messages.dart b/pkg/intl/lib/extract_messages.dart
index 2a34a4330c38c950fb0c5e527364d2bc5db04a4b..412c3a88259001fab08a78826036872b1f08ba14 100644
--- a/pkg/intl/lib/extract_messages.dart
+++ b/pkg/intl/lib/extract_messages.dart
@@ -217,9 +217,9 @@ class MessageFindingVisitor extends GeneralizingASTVisitor {
       Function setAttribute) {
     var message = new MainMessage();
     message.name = name;
-    message.arguments = parameters.parameters.elements.map(
+    message.arguments = parameters.parameters.map(
         (x) => x.identifier.name).toList();
-    var arguments = node.argumentList.arguments.elements;
+    var arguments = node.argumentList.arguments;
     extract(message, arguments);
 
     for (var namedArgument in arguments.where((x) => x is NamedExpression)) {
@@ -446,7 +446,7 @@ class PluralAndGenderVisitor extends SimpleASTVisitor {
         warnings.add(err);
       }
     });
-    var mainArg = node.argumentList.arguments.elements.firstWhere(
+    var mainArg = node.argumentList.arguments.firstWhere(
         (each) => each is! NamedExpression);
     if (mainArg is SimpleStringLiteral) {
       message.mainArgument = mainArg.toString();