Deprecate Math object in corelib in favor of dart:math library.

samples/solar/solar.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.
 
 /**
  * A solar system visualization.
  */
 
 #library("solar");
 
 #import("dart:html");
+#import("dart:math", prefix: "Math");
 
 /**
  * The entry point to the application.
  */
 void main() {
   var solarSystem = new SolarSystem(query("#container"));
 
   solarSystem.start();
 }
 
@@ skipping 238 matching lines @@
     } else {
       num angle = solarSystem.renderTime * orbitSpeed;
 
       return new Point(
         orbitRadius * Math.cos(angle) + x,
         orbitRadius * Math.sin(angle) + y);
     }
   }
 
 }