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

tools/dom/templates/html/impl/impl_CustomEvent.darttemplate

Index: tools/dom/templates/html/impl/impl_CustomEvent.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_CustomEvent.darttemplate b/tools/dom/templates/html/impl/impl_CustomEvent.darttemplate
index e16b74a9fe70544719c8c305ed173fd36c9c8a5a..29feca967a1d61c47a2f9107a27be4376d099eb8 100644
--- a/tools/dom/templates/html/impl/impl_CustomEvent.darttemplate
+++ b/tools/dom/templates/html/impl/impl_CustomEvent.darttemplate
@@ -34,11 +34,6 @@ $endif
       e._initCustomEvent(type, canBubble, cancelable, null);
     }
 
-$if DARTIUM
-    // Need for identity.
-    js.setDartHtmlWrapperFor(e.blink_jsObject, e);
-
-$endif
     return e;
   }