Type extension support in polyfill.

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 325 matching lines @@
    *     var myElement = new Element.tag('unknownTag');
    *     print(myElement is UnknownElement); // 'true'
    *
    * For standard elements it is more preferable to use the type constructors:
    *     var element = new DivElement();
    *
    * See also:
    *
    * * [isTagSupported]
    */
-  factory $CLASSNAME.tag(String tag) =>
-      _$(CLASSNAME)FactoryProvider.createElement_tag(tag);
+  factory $CLASSNAME.tag(String tag, [String typeExtention]) =>
+      _$(CLASSNAME)FactoryProvider.createElement_tag(tag, typeExtention);
 
   /// Creates a new `<a>` element.
   ///
   /// This is identical to calling `new Element.tag('a')`.
   factory Element.a() => new Element.tag('a');
 
   /// Creates a new `<article>` element.
   ///
   /// This is identical to calling `new Element.tag('article')`.
   factory Element.article() => new Element.tag('article');
@@ skipping 296 matching lines @@
   void appendHtml(String text) {
     this.insertAdjacentHtml('beforeend', text);
   }
 
   /**
    * Checks to see if the tag name is supported by the current platform.
    *
    * The tag should be a valid HTML tag name.
    */
   static bool isTagSupported(String tag) {
-    var e = _ElementFactoryProvider.createElement_tag(tag);
+    var e = _ElementFactoryProvider.createElement_tag(tag, null);
     return e is Element && !(e is UnknownElement);
   }
 
   /**
    * Called by the DOM when this element has been instantiated.
    */
   @Experimental()
   void created() {}
 
   // Hooks to support custom WebComponents.
@@ skipping 623 matching lines @@
   static Node _singleNode(List<Node> list) {
     if (list.length == 1) return list[0];
     throw new ArgumentError('HTML had ${list.length} '
         'top level elements but 1 expected');
   }
 
   @DomName('Document.createElement')
 $if DART2JS
   // Optimization to improve performance until the dart2js compiler inlines this
   // method.
-  static dynamic createElement_tag(String tag) =>
-      // Firefox may return a JS function for some types (Embed, Object).
-      JS('Element|=Object', 'document.createElement(#)', tag);
+  static dynamic createElement_tag(String tag, String typeExtension) =>
+    // Firefox may return a JS function for some types (Embed, Object).
+    JS('Element|=Object', 'document.createElement(#, #)', tag, typeExtension);
 $else
-  static Element createElement_tag(String tag) =>
-      document.$dom_createElement(tag);
+  static Element createElement_tag(String tag, String typeExtension) =>
+      document.$dom_createElement(tag, typeExtension);
 $endif
 }
 
 
 /**
  * Options for Element.scrollIntoView.
  */
 class ScrollAlignment {
   final _value;
   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');
 }