Fix a type error in Primitives.applyFunction.

dart/sdk/lib/_internal/compiler/implementation/lib/js_helper.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 _js_helper;
 
 import 'dart:collection';
 import 'dart:_foreign_helper' show DART_CLOSURE_TO_JS,
                                    JS,
                                    JS_CALL_IN_ISOLATE,
@@ skipping 507 matching lines @@
 
   static void setProperty(object, key, value) {
     if (object == null || object is bool || object is num || object is String) {
       throw new ArgumentError(object);
     }
     JS('void', '#[#] = #', object, key, value);
   }
 
   static applyFunction(Function function,
                        List positionalArguments,
-                       Map<Symbol, dynamic> namedArguments) {
+                       Map<String, dynamic> namedArguments) {
     int argumentCount = 0;
     StringBuffer buffer = new StringBuffer();
     List arguments = [];
 
     if (positionalArguments != null) {
       argumentCount += positionalArguments.length;
       arguments.addAll(positionalArguments);
     }
 
     // Sort the named arguments to get the right selector name and
     // arguments order.
     if (namedArguments != null && !namedArguments.isEmpty) {
       // Call new List.from to make sure we get a JavaScript array.
-      List<Symbol> listOfNamedArguments =
-          new List<Symbol>.from(namedArguments.keys);
+      List<String> listOfNamedArguments =
+          new List<String>.from(namedArguments.keys);
       argumentCount += namedArguments.length;
       // We're sorting on strings, and the behavior is the same between
       // Dart string sort and JS string sort. To avoid needing the Dart
       // sort implementation, we use the JavaScript one instead.
       JS('void', '#.sort()', listOfNamedArguments);
-      listOfNamedArguments.forEach((Symbol name) {
+      listOfNamedArguments.forEach((String name) {
         buffer.write('\$$name');
         arguments.add(namedArguments[name]);
       });
     }
 
     String selectorName = 'call\$$argumentCount$buffer';
     var jsFunction = JS('var', '#[#]', function, selectorName);
     if (jsFunction == null) {
       throw new NoSuchMethodError(function, selectorName, arguments, {});
     }
@@ skipping 821 matching lines @@
                               expectedArgumentNames);
 }
 
 /**
  * Called by generated code when a static field's initializer references the
  * field that is currently being initialized.
  */
 void throwCyclicInit(String staticName) {
   throw new RuntimeError("Cyclic initialization for static $staticName");
 }