Use named arguments for messages.

sdk/lib/_internal/compiler/implementation/elements/elements.dart

 // Copyright (c) 2012, 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 elements;
 
 import 'dart:uri';
 
 import 'modelx.dart';
 import '../tree/tree.dart';
@@ skipping 426 matching lines @@
     return a.hashCode.compareTo(b.hashCode);
   }
 
   static List<Element> sortedByPosition(Iterable<Element> elements) {
     return elements.toList()..sort(compareByPosition);
   }
 }
 
 abstract class ErroneousElement extends Element implements FunctionElement {
   MessageKind get messageKind;
-  List get messageArguments;
+  Map get messageArguments;
 }
 
 abstract class AmbiguousElement extends Element {
   MessageKind get messageKind;
-  List get messageArguments;
+  Map get messageArguments;
   Element get existingElement;
   Element get newElement;
 }
 
 // TODO(kasperl): This probably shouldn't be called an element. It's
 // just an interface shared by classes and libraries.
 abstract class ScopeContainerElement {
   Element localLookup(SourceString elementName);
 }
 
@@ skipping 315 matching lines @@
   Element get annotatedElement;
   int get resolutionState;
   Token get beginToken;
 
   // TODO(kasperl): Try to get rid of these.
   void set annotatedElement(Element value);
   void set resolutionState(int value);
 
   MetadataAnnotation ensureResolved(Compiler compiler);
 }