Mock up all remaining core library implementation classes.

dart/frog/leg/lib/core.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('core');
 
 #import('coreimpl.dart');
 
 #import('js_helper.dart'); // TODO(ahe): remove this import.
 
@@ skipping 21 matching lines @@
 #source('../../../corelib/src/promise.dart');
 #source('../../../corelib/src/queue.dart');
 #source('../../../corelib/src/regexp.dart');
 #source('../../../corelib/src/set.dart');
 #source('../../../corelib/src/stopwatch.dart');
 #source('../../../corelib/src/string.dart');
 #source('../../../corelib/src/string_buffer.dart');
 #source('../../../corelib/src/strings.dart');
 #source('../../../corelib/src/time_zone.dart');
 #source('mock.dart');
+#source('clock.dart');
 
 void print(var obj) => Primitives.printString(obj.toString());
 
 class Object {
   String toString() => Primitives.objectToString(this);
 
   void noSuchMethod(String name, List args) {
     throw new NoSuchMethodException(this, name, args);
   }
 }