Rename Date to DateTime.

runtime/lib/math_patch.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 VM patch of the dart:math library.
 patch num pow(num x, num exponent) {
   if (exponent is int) {
     return x.pow(exponent);
   }
   // Double.pow will call exponent.toDouble().
@@ skipping 93 matching lines @@
   static const _POW2_53_D = 1.0 * (1 << 53);
 
   static const _A = 0xffffda61;
 
   // Use a singleton Random object to get a new seed if no seed was passed.
   static var _prng = null;
 
   static int _nextSeed() {
     if (_prng == null) {
       // TODO(iposva): Use system to get a random seed.
-      _prng = new Random(new Date.now().millisecondsSinceEpoch);
+      _prng = new Random(new DateTime.now().millisecondsSinceEpoch);
     }
     // Trigger the PRNG once to change the internal state.
     return _prng._nextInt32();
   }
 }