Prototype of Dart proxies for JS objects.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 3cc7cd5c47e8b433f1f15063696c152a3b32233e..010b36274a201cc9069ccbd4c31d4272dbb78b48 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -12688,18 +12688,18 @@ class ElementEvents extends Events {
   /* Raw event target. */
   final Element _ptr;
   static final webkitEvents = {
-    'animationend' : 'webkitAnimationEnd', 
-    'animationiteration' : 'webkitAnimationIteration', 
-    'animationstart' : 'webkitAnimationStart', 
-    'fullscreenchange' : 'webkitfullscreenchange', 
+    'animationend' : 'webkitAnimationEnd',
+    'animationiteration' : 'webkitAnimationIteration',
+    'animationstart' : 'webkitAnimationStart',
+    'fullscreenchange' : 'webkitfullscreenchange',
     'fullscreenerror' : 'webkitfullscreenerror',
-    'keyadded' : 'webkitkeyadded', 
-    'keyerror' : 'webkitkeyerror', 
-    'keymessage' : 'webkitkeymessage', 
-    'needkey' : 'webkitneedkey', 
-    'pointerlockchange' : 'webkitpointerlockchange', 
-    'pointerlockerror' : 'webkitpointerlockerror', 
-    'resourcetimingbufferfull' : 'webkitresourcetimingbufferfull', 
+    'keyadded' : 'webkitkeyadded',
+    'keyerror' : 'webkitkeyerror',
+    'keymessage' : 'webkitkeymessage',
+    'needkey' : 'webkitneedkey',
+    'pointerlockchange' : 'webkitpointerlockchange',
+    'pointerlockerror' : 'webkitpointerlockerror',
+    'resourcetimingbufferfull' : 'webkitresourcetimingbufferfull',
     'transitionend': 'webkitTransitionEnd',
     'speechchange' : 'webkitSpeechChange'
   };
@@ -14872,32 +14872,6 @@ class HtmlDocument extends Document {
    * 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 extendsTag}) {
     _Utils.register(this, tag, customElementClass, extendsTag);
@@ -14928,6 +14902,33 @@ class HtmlDocument extends Document {
   @Experimental()
   Stream<Event> get onVisibilityChange =>
       visibilityChangeEvent.forTarget(this);
+
+  ElementUpgrader createElementUpgrader(Type type, [String tagName]) {
+  }
+
+}
+
+
+
+abstract class ElementUpgrader {
+  // Validate that e is subclass of type's native type
+  // validate that e has not been upgraded as any type
+  Element upgrade(Element element);
+}
+
+class _VMElementUpgrader implements ElementUpgrader {
+  final Type _type;
+  Type _nativeType;
+  _VMElementUpgrader(Type type) :
+      _type = type,
+      _nativeType = _Utils.validateCustomType(type).reflectedType;
+
+  Element upgrade(Element element) {
+    if (element.runtimeType != _nativeType) {
+      throw new UnsupportedError('Element is incorrect type');
+    }
+    return null;
+  }
 }
 // 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
@@ -28955,13 +28956,13 @@ class Url extends NativeFieldWrapperClass2 implements UrlUtils {
     if ((blob_OR_source_OR_stream is Blob || blob_OR_source_OR_stream == null)) {
       return _createObjectURL_1(blob_OR_source_OR_stream);
     }
-    if ((blob_OR_source_OR_stream is MediaSource || blob_OR_source_OR_stream == null)) {
+    if ((blob_OR_source_OR_stream is MediaStream || blob_OR_source_OR_stream == null)) {
       return _createObjectURL_2(blob_OR_source_OR_stream);
     }
-    if ((blob_OR_source_OR_stream is _WebKitMediaSource || blob_OR_source_OR_stream == null)) {
+    if ((blob_OR_source_OR_stream is MediaSource || blob_OR_source_OR_stream == null)) {
       return _createObjectURL_3(blob_OR_source_OR_stream);
     }
-    if ((blob_OR_source_OR_stream is MediaStream || blob_OR_source_OR_stream == null)) {
+    if ((blob_OR_source_OR_stream is _WebKitMediaSource || blob_OR_source_OR_stream == null)) {
       return _createObjectURL_4(blob_OR_source_OR_stream);
     }
     throw new ArgumentError("Incorrect number or type of arguments");
@@ -38698,8 +38699,14 @@ class _Utils {
     return libName.startsWith('dart:');
   }
 
-  static void register(Document document, String tag, Type type,
-      String extendsTagName) {
+  /// Validates that the custom type is properly formed-
+  ///
+  /// * Is a user-defined class.
+  /// * Has a created constructor with zero args.
+  /// * Derives from an Element subclass.
+  ///
+  /// Then returns the native base class.
+  static ClassMirror validateCustomType(Type type) {
     // TODO(vsm): Move these checks into native code.
     ClassMirror cls = reflectClass(type);
     if (_isBuiltinType(cls)) {
@@ -38733,6 +38740,13 @@ class _Utils {
         nativeClass = superClass;
       }
     }
+    return nativeClass;
+  }
+
+  static void register(Document document, String tag, Type type,
+      String extendsTagName) {
+    var nativeClass = validateCustomType(type);
+
     if (extendsTagName == null) {
       if (nativeClass.reflectedType != HtmlElement) {
         throw new UnsupportedError('Class must provide extendsTag if base '