Revert "Port the remaining of dart:coreimpl to the unified corelib."

lib/compiler/implementation/lib/clock.dart

Index: lib/compiler/implementation/lib/clock.dart
diff --git a/runtime/lib/clock.dart b/lib/compiler/implementation/lib/clock.dart
similarity index 70%
copy from runtime/lib/clock.dart
copy to lib/compiler/implementation/lib/clock.dart
index 2dc2f3303963cb74be6286ce011156c0c417fbfb..c9a1edddd15be7a3e7bbad1f1694246929a778f8 100644
--- a/runtime/lib/clock.dart
+++ b/lib/compiler/implementation/lib/clock.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -11,11 +11,10 @@ class Clock {
   /**
    * Returns the current clock tick.
    */
-  static int now() native "Clock_now";
+  static int now() => Primitives.dateNow();
 
   /**
    * Returns the frequency of clock ticks in Hz.
    */
-  static int frequency() native "Clock_frequency";
-
+  static int frequency() => 1000;
 }