Optimize dartium dart:html bindings so real world application performance is acceptable. Improves d…

tools/dom/src/dartium_WrappedEvent.dart

Index: tools/dom/src/dartium_WrappedEvent.dart
diff --git a/tools/dom/src/dartium_WrappedEvent.dart b/tools/dom/src/dartium_WrappedEvent.dart
index 2364158e0caedd45ebcc41ddacd6d36200b0ab6f..a4e0ace767910038d7ee7c7a627b1dc162c28c24 100644
--- a/tools/dom/src/dartium_WrappedEvent.dart
+++ b/tools/dom/src/dartium_WrappedEvent.dart
@@ -6,15 +6,14 @@ part of dart.html;
 
 /**
  * Helper class to implement custom events which wrap DOM events.
+ * TODO(jacobr): consider using dart JsNative.$setInstanceInterceptor
+ * instead of using wrappers as that would allow passing these wrappers
+ * back through dispatchEvent unlike the current implementation.
+ * See https://github.com/dart-lang/sdk/issues/16869
  */
 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. */