Adding polyfill support for custom elements.

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 226 matching lines @@
    * border + margin box in this list.
    *
    * This returns a rectangle with the dimenions actually available for content
    * in this element, in pixels, regardless of this element's box-sizing
    * property. Unlike [getBoundingClientRect], the dimensions of this rectangle
    * will return the same numerical height if the element is hidden or not. This
    * can be used to retrieve jQuery's `outerHeight` value for an element.
    */
   @Experimental()
   CssRect get marginEdge;
-$!STREAM_GETTER_SIGNATURES 
+$!STREAM_GETTER_SIGNATURES
 }
 
 // TODO(jacobr): this is an inefficient implementation but it is hard to see
 // a better option given that we cannot quite force NodeList to be an
 // ElementList as there are valid cases where a NodeList JavaScript object
 // contains Node objects that are not Elements.
 class _FrozenElementList<T extends Element> extends ListBase<T> implements ElementList {
   final List<Node> _nodeList;
   // The subset of _nodeList that are Elements.
   List<Element> _elementList;
@@ skipping 905 matching lines @@
     bool foundAsParent = identical(current, parent) || parent.tagName == 'HTML';
     if (current == null || identical(current, parent)) {
       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);
   }
+
+$if DART2JS
+  @JSName('innerHTML')
+  @DomName('HTMLElement.innerHTML')
+  String get innerHtml;
+
+  void set innerHtml(String value) {
+    JS('', '#.innerHTML = #', this, value);
+    // Polyfill relies on mutation observers for upgrading, but we want it
+    // immediate.
+    Platform.upgradeCustomElements(this);
+  }
+$endif
+
 $!MEMBERS
 }
 
 final _START_TAG_REGEXP = new RegExp('<(\\w+)');
 class _ElementFactoryProvider {
   static const _CUSTOM_PARENT_TAG_MAP = const {
     'body' : 'html',
     'head' : 'html',
     'caption' : 'table',
     'td': 'tr',
@@ skipping 126 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');
 }