const constructors with optional arguments.

frog/leg/universe.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.
 
 class Universe {
   Map<Element, String> generatedCode;
   Map<Element, String> generatedBailoutCode;
   final Set<ClassElement> instantiatedClasses;
   final Set<SourceString> instantiatedClassInstanceFields;
   final Set<FunctionElement> staticFunctionsNeedingGetter;
@@ skipping 131 matching lines @@
     int positionalArgumentCount = this.positionalArgumentCount;
     for (int i = 0;
          i < positionalArgumentCount;
          arguments = arguments.tail, i++) {
       list.add(visitArgument(arguments.head));
     }
 
     // Visit named arguments and add them into a temporary list.
     List namedArguments = [];
     for (; !arguments.isEmpty(); arguments = arguments.tail) {
-      namedArguments.add(visitArgument(arguments.head));
+      NamedArgument namedArgument = arguments.head;
+      namedArguments.add(visitArgument(namedArgument.expression));
     }
 
     Link<Element> remainingNamedParameters = parameters.optionalParameters;
     // Skip the optional parameters that have been given in the
     // positional arguments.
     for (int i = parameters.requiredParameterCount;
          i < positionalArgumentCount;
          i++) {
       remainingNamedParameters = remainingNamedParameters.tail;
     }
@@ skipping 59 matching lines @@
     if (!orderedNamedArguments.isEmpty()) return orderedNamedArguments;
 
     List<SourceString> list = new List<SourceString>.from(namedArguments);
     list.sort((SourceString first, SourceString second) {
       return first.slowToString().compareTo(second.slowToString());
     });
     orderedNamedArguments = list;
     return orderedNamedArguments;
   }
 }