Move the individual property definitions from client/base/Css to CSSStyleDeclaration.

client/view/SliderMenu.dart

 // Copyright (c) 2011, 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.
 
 typedef void SelectHandler(String menuText);
 
 /**
  * This implements a horizontal menu bar with a sliding triangle arrow
  * that points at the currently selected item.
  */
@@ skipping 146 matching lines @@
     if (selectedItem != null) {
       // calculate where we want to put the triangle
       x = selectedItem.offsetLeft +
           selectedItem.offsetWidth / 2 - TRIANGLE_WIDTH / 2;
     }
 
     // find the slider filler (the div element to the left of the
     // triangle) set its width the push the triangle to where we want it.
     String duration = animate ? '.3s' : '0s';
     final triangle = node.query('.sm-triangle');
-    Css.setTransitionDuration(triangle.style, duration);
+    triangle.style.transitionDuration = duration;
     FxUtil.setWebkitTransform(triangle, x, 0);
   }
 }