Switch dart:html objects not to be NativeFieldWrapper subclasses with JsInterop

sdk/lib/js/dartium/js_dartium.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Support for interoperating with JavaScript.
  *
  * This library provides access to JavaScript objects from Dart, allowing
  * Dart code to get and set properties, and call methods of JavaScript objects
  * and invoke JavaScript functions. The library takes care of converting
@@ skipping 715 matching lines @@
 void setDartHtmlWrapperFor(JsObject object, wrapper) {
   object._dartHtmlWrapper = wrapper;
 }
 
 /**
  * Used by callMethod to get the JS object for each argument passed if the
  * argument is a Dart class instance that delegates to a DOM object.  See
  * wrap_jso defined in dart:html.
  */
 unwrap_jso(dartClass_instance) {
-  if (dartClass_instance is NativeFieldWrapperClass2 && dartClass_instance is! JsObject)
+  if (dartClass_instance is html.DartHtmlDomObject)
     return dartClass_instance.blink_jsObject;
   else
     return dartClass_instance;
 }
 
 /**
  * Proxies a JavaScript object to Dart.
  *
  * The properties of the JavaScript object are accessible via the `[]` and
  * `[]=` operators. Methods are callable via [callMethod].
@@ skipping 427 matching lines @@
     return f;
   } else {
     var ret = _interopCaptureThisExpando[f];
     if (ret == null) {
       ret = new JsFunction.withThis(f);
       _interopCaptureThisExpando[f] = ret;
     }
     return ret;
   }
 }