Fixed custom elements to work in Polymer

tools/dom/templates/html/dartium/html_dartium.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.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
 
 /**
  * HTML elements and other resources for web-based applications that need to
  * interact with the browser and the DOM (Document Object Model).
@@ skipping 352 matching lines @@
 // wrap_jso calls.
 bool __interop_checks = true;
 
 /** Expando for JsObject, used by every Dart class associated with a Javascript
  *  class (e.g., DOM, WebAudio, etc.).
  */
 
 /**
  * Return the JsObject associated with a Dart class [dartClass_instance].
  */
-unwrap_jso(dartClass_instance) {
-  try {
-    if (dartClass_instance != null)
-      return dartClass_instance is NativeFieldWrapperClass2 ?
-          dartClass_instance.blink_jsObject : dartClass_instance;
-    else
-      return null;
-  } catch(NoSuchMethodException) {
-    // No blink_jsObject then return the dartClass_instance is probably an
-    // array that was already converted to a Dart class e.g., Uint8ClampedList.
-    return dartClass_instance;
-  }
-}
+unwrap_jso(dartClass_instance) => js.unwrap_jso(dartClass_instance);
 
 /**
  * Create Dart class that maps to the JS Type, add the JsObject as an expando
  * on the Dart class and return the created Dart class.
  */
 wrap_jso(jsObject) {
   try {
     if (jsObject is! js.JsObject || jsObject == null) {
       // JS Interop converted the object to a Dart class e.g., Uint8ClampedList.
       // or it's a simple type.
@@ skipping 168 matching lines @@
   final js.JsArray _basicList;
 
   operator [](int index) => wrap_jso(_basicList[index]);
 
   operator []=(int index, value) => _basicList[index] = unwrap_jso(value);
 
   int get length => _basicList.length;
   int set length(int newLength) => _basicList.length = newLength;
 }
 
+/**
+ * Upgrade the JS HTMLElement to the Dart class.  Used by Dart's Polymer.
+ */
+createCustomUpgrader(Type customElementClass, $this) {
+  var dartClass;
+  try {
+    dartClass = _blink.Blink_Utils.constructElement(customElementClass, $this);
+  } catch (e) {
+    throw e;
+  } finally {
+    // Need to remember the Dart class that was created for this custom so
+    // return it and setup the blink_jsObject to the $this that we'll be working
+    // with as we talk to blink. 
+    $this['dart_class'] = dartClass;
+  }
+
+  return dartClass;
+}
+
 $else
 class JsoNativeFieldWrapper extends NativeFieldWrapperClass2 {}
 
 unwrap_jso(dartClass_instance) => dartClass_instance;
 wrap_jso(jsObject) => jsObject;
 make_dart_rectangle(r) => r;
 convertDartToNative_Dictionary(Map dict) => dict;
 List convertDartToNative_StringArray(List<String> input) => input;
 convertDartToNative_List(List input) => input;
+createCustomUpgrader(Type customElementClass, $this) => $this;
 
 $endif