Revert "Dartium JS Interop enabled."

tools/dom/src/dartium_WrappedEvent.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.
 
 part of dart.html;
 
 /**
  * Helper class to implement custom events which wrap DOM events.
  */
 class _WrappedEvent implements Event {
-  /** Needed because KeyboardEvent is implements.
-   *  TODO(terry): Consider making blink_jsObject private (add underscore) for
-   *               all blink_jsObject.  Then needed private wrap/unwrap_jso
-   *               functions that delegate to a public wrap/unwrap_jso.
-   */
-  js.JsObject blink_jsObject;
-
   final Event wrapped;
 
   /** The CSS selector involved with event delegation. */
   String _selector;
 
   _WrappedEvent(this.wrapped);
 
   bool get bubbles => wrapped.bubbles;
 
   bool get cancelable => wrapped.cancelable;
@@ skipping 56 matching lines @@
    * ## Other resources
    *
    * * [Shadow DOM extensions to Event]
    * (http://w3c.github.io/webcomponents/spec/shadow/#extensions-to-event) from
    * W3C.
    */
   // https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#extensions-to-event
   @Experimental()
   List<Node> get path => wrapped.path;
 }