Implement constant maps.

frog/leg/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('coreimpl.dart');
 
+#source('constant_map.dart');
 #source('date_helper.dart');
 #source('regexp_helper.dart');
 #source('string_helper.dart');
 
 /**
  * Returns true if both arguments are numbers.
  *
  * If only the first argument is a number, an
  * [IllegalArgumentException] with the other argument is thrown.
  */
@@ skipping 1342 matching lines @@
  */
 callClosure0(closure) => closure();
 callClosure1(closure, arg1) => closure(arg1);
 callClosure2(closure, arg1, arg2) => closure(arg1, arg2);
 
 class StackTrace {
   var stack;
   StackTrace(this.stack);
   String toString() => stack != null ? stack : '';
 }
+
+bool jsHasOwnProperty(var jsObject, String property) {
+  return JS('bool', @'$0.hasOwnProperty($1)', jsObject, property);
+}
+
+jsPropertyAccess(var jsObject, String property) {
+  return JS('var', @'$0[$1]', jsObject, property);
+}