Optimization for Element.innerHtml

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> {
   // Raw Element.
   final Element _element;
   final HtmlCollection _childElements;
@@ skipping 1171 matching lines @@
       if (foundAsParent) return new Point(0, 0);
       throw new ArgumentError("Specified element is not a transitive offset "
           "parent of this element.");
     }
     Element parentOffset = current.offsetParent;
     Point p = Element._offsetToHelper(parentOffset, parent);
     return new Point(p.x + current.offsetLeft, p.y + current.offsetTop);
   }
 
   static HtmlDocument _parseDocument;
+  static Range _parseRange;
   static NodeValidatorBuilder _defaultValidator;
   static _ValidatingTreeSanitizer _defaultSanitizer;
 
   /**
    * Create a DocumentFragment from the HTML fragment and ensure that it follows
    * the sanitization rules specified by the validator or treeSanitizer.
    *
    * If the default validation behavior is too restrictive then a new
    * NodeValidator should be created, either extending or wrapping a default
    * validator and overriding the validation APIs.
@@ skipping 25 matching lines @@
         _defaultSanitizer.validator = validator;
       }
       treeSanitizer = _defaultSanitizer;
     } else if (validator != null) {
       throw new ArgumentError(
           'validator can only be passed if treeSanitizer is null');
     }
 
     if (_parseDocument == null) {
       _parseDocument = document.implementation.createHtmlDocument('');
+      _parseRange = _parseDocument.createRange();
     }
     var contextElement;
     if (this is BodyElement) {
       contextElement = _parseDocument.body;
     } else {
       contextElement = _parseDocument.$dom_createElement(tagName);
       _parseDocument.body.append(contextElement);
     }
     var fragment;
     if (Range.supportsCreateContextualFragment) {
-      var range = _parseDocument.createRange();
-      range.selectNodeContents(contextElement);
-      fragment = range.createContextualFragment(html);
+      _parseRange.selectNodeContents(contextElement);
+      fragment = _parseRange.createContextualFragment(html);
     } else {
       contextElement._innerHtml = html;
 
       fragment = _parseDocument.createDocumentFragment();
       while (contextElement.firstChild != null) {
         fragment.append(contextElement.firstChild);
       }
     }
     if (contextElement != _parseDocument.body) {
       contextElement.remove();
@@ skipping 79 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');
 }