Revert r5529. Breaks frog and web bots.

frog/leg/resolver.dart

Index: frog/leg/resolver.dart
===================================================================
--- frog/leg/resolver.dart	(revision 5530)
+++ frog/leg/resolver.dart	(working copy)
@@ -813,7 +813,6 @@
   void handleArguments(Send node) {
     int count = 0;
     List<SourceString> namedArguments = <SourceString>[];
-    bool seenNamedArgument = false;
     for (Link<Node> link = node.argumentsNode.nodes;
          !link.isEmpty();
          link = link.tail) {
@@ -821,11 +820,8 @@
       Expression argument = link.head;
       visit(argument);
       if (argument.asNamedArgument() != null) {
-        seenNamedArgument = true;
         NamedArgument named = argument;
         namedArguments.add(named.name.source);
-      } else if (seenNamedArgument) {
-        error(argument, MessageKind.INVALID_ARGUMENT_AFTER_NAMED);
       }
     }
     mapping.setSelector(node, new Invocation(count, namedArguments));