Parse and resolve new syntax for named parameters.

dart/lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   DartType getType(TypeAnnotation annotation);
   bool isParameterChecked(Element element);
 }
@@ skipping 2307 matching lines @@
 class SignatureResolver extends CommonResolverVisitor<Element> {
   final Element enclosingElement;
   Link<Element> optionalParameters = const EmptyLink<Element>();
   int optionalParameterCount = 0;
   VariableDefinitions currentDefinitions;
 
   SignatureResolver(Compiler compiler, this.enclosingElement) : super(compiler);
 
   Element visitNodeList(NodeList node) {
     // This must be a list of optional arguments.
-    if (node.beginToken.stringValue !== '[') {
+    String value = node.beginToken.stringValue;
+    if ((value !== '[') && (value !== '{')) {
       internalError(node, "expected optional parameters");
     }
     LinkBuilder<Element> elements = analyzeNodes(node.nodes);
     optionalParameterCount = elements.length;
     optionalParameters = elements.toLink();
     return null;
   }
 
   Element visitVariableDefinitions(VariableDefinitions node) {
     Link<Node> definitions = node.definitions.nodes;
@@ skipping 412 matching lines @@
 
   Element localLookup(SourceString name) => library.find(name);
   Element lookup(SourceString name) => localLookup(name);
   Element lexicalLookup(SourceString name) => localLookup(name);
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
   String toString() => '$element';
 }