Fix + usages.

samples/ui_lib/view/ConveyorView.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.
 
 /**
  * Holds a number of child views.  As you switch between views, the old
  * view is pushed off to the side and the new view slides in from the other
  * side.
  */
 class ConveyorView extends CompositeView {
@@ skipping 68 matching lines @@
     }
     throw "view not found";
   }
 
   /**
    * Adds a child view to the ConveyorView.  The views are stacked horizontally
    * in the order they are added.
    */
   View addChild(View view) {
     view.addClass('conveyor-item');
-    view.transform = 'translate3d(' + (childViews.length * 100) + '%, 0, 0)';
+    view.transform = 'translate3d(${(childViews.length * 100)}%, 0, 0)';
     return super.addChild(view);
   }
 
   void _onAnimationEnd() {
     if (viewSelected != null) {
       viewSelected(selectedView);
     }
   }
 }