Optimization for Element.innerHtml

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

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 4c1a75ac3fc024c516763035e5138a04addf92ff..1a556b29842d2ec756d87dd2cafeae81a9126e29 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -1189,6 +1189,7 @@ $endif
   }
 
   static HtmlDocument _parseDocument;
+  static Range _parseRange;
   static NodeValidatorBuilder _defaultValidator;
   static _ValidatingTreeSanitizer _defaultSanitizer;
 
@@ -1234,6 +1235,7 @@ $endif
 
     if (_parseDocument == null) {
       _parseDocument = document.implementation.createHtmlDocument('');
+      _parseRange = _parseDocument.createRange();
     }
     var contextElement;
     if (this is BodyElement) {
@@ -1244,9 +1246,8 @@ $endif
     }
     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;