Speeding up ElementList.clear & NodeList.clear.

tools/dom/templates/html/impl/impl_Element.darttemplate

 // 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.
 
 part of $LIBRARYNAME;
 
 class _ChildrenElementList extends ListBase<Element>
     implements NodeListWrapper {
   // Raw Element.
   final Element _element;
@@ skipping 103 matching lines @@
     } else {
       _element.insertBefore(element, this[index]);
     }
   }
 
   void setAll(int index, Iterable<Element> iterable) {
     throw new UnimplementedError();
   }
 
   void clear() {
-    // It is unclear if we want to keep non element nodes?
-    _element.text = '';
+    _element._clearChildren();
   }
 
   Element removeAt(int index) {
     final result = this[index];
     if (result != null) {
       _element._removeChild(result);
     }
     return result;
   }
 
@@ skipping 1204 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }