Type extension support in polyfill.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index a6b0e8154f4023b46014e3567796d8b470bc4129..3a717a83d8f600274feea6b74e80e1584105a25e 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -8826,8 +8826,8 @@ abstract class Element extends Node implements ParentNode, ChildNode native "Ele
    *
    * * [isTagSupported]
    */
-  factory Element.tag(String tag) =>
-      _ElementFactoryProvider.createElement_tag(tag);
+  factory Element.tag(String tag, [String typeExtention]) =>
+      _ElementFactoryProvider.createElement_tag(tag, typeExtention);
 
   /// Creates a new `<a>` element.
   ///
@@ -9144,7 +9144,7 @@ abstract class Element extends Node implements ParentNode, ChildNode native "Ele
    * 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);
   }
 
@@ -10586,9 +10586,19 @@ class _ElementFactoryProvider {
   @DomName('Document.createElement')
   // 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).
+    if (typeExtension != null) {
+      return JS('Element|=Object', 'document.createElement(#, #)',
+          tag, typeExtension);
+    }
+    // Should be able to eliminate this and just call the two-arg version above
+    // with null typeExtension, but Chrome treats the tag as case-sensitive if
+    // typeExtension is null.
+    // https://code.google.com/p/chromium/issues/detail?id=282467
+    return JS('Element|=Object', 'document.createElement(#)', tag);
+  }
+
 }
 
 
@@ -12695,8 +12705,76 @@ class HtmlDocument extends Document native "HTMLDocument" {
   String get visibilityState => _webkitVisibilityState;
 
   @Experimental
-  void register(String tag, Type customElementClass) {
-    _registerCustomElement(JS('', 'window'), this, tag, customElementClass);
+  /**
+   * Register a custom subclass of Element to be instantiatable by the DOM.
+   *
+   * This is necessary to allow the construction of any custom elements.
+   *
+   * The class being registered must either subclass HtmlElement or SvgElement.
+   * If they subclass these directly then they can be used as:
+   *
+   *     class FooElement extends HtmlElement{
+   *        void created() {
+   *          print('FooElement created!');
+   *        }
+   *     }
+   *
+   *     main() {
+   *       document.register('x-foo', FooElement);
+   *       var myFoo = new Element.tag('x-foo');
+   *       // prints 'FooElement created!' to the console.
+   *     }
+   *
+   * The custom element can also be instantiated via HTML using the syntax
+   * `<x-foo></x-foo>`
+   *
+   * Other elements can be subclassed as well:
+   *
+   *     class BarElement extends InputElement{
+   *        void created() {
+   *          print('BarElement created!');
+   *        }
+   *     }
+   *
+   *     main() {
+   *       document.register('x-bar', BarElement);
+   *       var myBar = new Element.tag('input', 'x-bar');
+   *       // prints 'BarElement created!' to the console.
+   *     }
+   *
+   * This custom element can also be instantiated via HTML using the syntax
+   * `<input is="x-bar"></input>`
+   *
+   * The [nativeTagName] parameter is needed by platforms without native support
+   * when subclassing a native type other than:
+   *
+   * * HtmlElement
+   * * SvgElement
+   * * AnchorElement
+   * * AudioElement
+   * * ButtonElement
+   * * CanvasElement
+   * * DivElement
+   * * ImageElement
+   * * InputElement
+   * * LIElement
+   * * LabelElement
+   * * MenuElement
+   * * MeterElement
+   * * OListElement
+   * * OptionElement
+   * * OutputElement
+   * * ParagraphElement
+   * * PreElement
+   * * ProgressElement
+   * * SelectElement
+   * * SpanElement
+   * * UListElement
+   * * VideoElement
+   */
+  void register(String tag, Type customElementClass, {String nativeTagName}) {
+    _registerCustomElement(JS('', 'window'), this, tag, customElementClass,
+        nativeTagName);
   }
 
   @Creates('Null')  // Set from Dart code; does not instantiate a native type.
@@ -31867,7 +31945,32 @@ _makeCreatedCallbackMethod() {
       convertDartClosureToJS(_callCreated, 1));
 }
 
-void _registerCustomElement(context, document, String tag, Type type) {
+const _typeNameToTag = const {
+  'HTMLAnchorElement': 'a',
+  'HTMLAudioElement': 'audio',
+  'HTMLButtonElement': 'button',
+  'HTMLCanvasElement': 'canvas',
+  'HTMLDivElement': 'div',
+  'HTMLImageElement': 'img',
+  'HTMLInputElement': 'input',
+  'HTMLLIElement': 'li',
+  'HTMLLabelElement': 'label',
+  'HTMLMenuElement': 'menu',
+  'HTMLMeterElement': 'meter',
+  'HTMLOListElement': 'ol',
+  'HTMLOptionElement': 'option',
+  'HTMLOutputElement': 'output',
+  'HTMLParagraphElement': 'p',
+  'HTMLPreElement': 'pre',
+  'HTMLProgressElement': 'progress',
+  'HTMLSelectElement': 'select',
+  'HTMLSpanElement': 'span',
+  'HTMLUListElement': 'ul',
+  'HTMLVideoElement': 'video',
+};
+
+void _registerCustomElement(context, document, String tag, Type type,
+    String nativeTagName) {
   // Function follows the same pattern as the following JavaScript code for
   // registering a custom element.
   //
@@ -31909,8 +32012,17 @@ void _registerCustomElement(context, document, String tag, Type type) {
 
   setNativeSubclassDispatchRecord(proto, interceptor);
 
-  JS('void', '#.register(#, #)',
-      document, tag, JS('', '{prototype: #}', proto));
+  var options = JS('=Object', '{prototype: #}', proto);
+
+  if (baseClassName != 'HTMLElement') {
+    if (nativeTagName != null) {
+      JS('=Object', '#.extends = #', options, nativeTagName);
+    } else if (_typeNameToTag.containsKey(baseClassName)) {
+      JS('=Object', '#.extends = #', options, _typeNameToTag[baseClassName]);
+    }
+  }
+
+  JS('void', '#.register(#, #)', document, tag, options);
 }
 // 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