Remove deprecated StringBuffer.add, addAll and addCharCode.

samples/swarm/swarm_ui_lib/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.
 
 part of view;
 
 typedef void SelectHandler(String menuText);
 
 /**
  * This implements a horizontal menu bar with a sliding triangle arrow
@@ skipping 18 matching lines @@
   SelectHandler onSelect;
 
   List<String> _menuItems;
 
   SliderMenu(this._menuItems, this.onSelect) : super() {}
 
   Element render() {
     // Create a div for each menu item.
     final items = new StringBuffer();
     for (final item in _menuItems) {
-      items.add('<div class="sm-item">$item</div>');
+      items.write('<div class="sm-item">$item</div>');
     }
 
     // Create a root node to hold this view.
     return new Element.html('''
         <div class="sm-root">
           <div class="sm-item-box">
             <div class="sm-item-filler"></div>
             $items
             <div class="sm-item-filler"></div>
           </div>
@@ skipping 119 matching lines @@
 
   void _moveIndicator(num x, bool animate) {
     // 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');
     triangle.style.transitionDuration = duration;
     FxUtil.setWebkitTransform(triangle, x, 0);
   }
 }