Removed DARTIUM codegen for IDLS (sdk/lib/dartium)

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

Index: tools/dom/templates/html/impl/impl_MessageEvent.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_MessageEvent.darttemplate b/tools/dom/templates/html/impl/impl_MessageEvent.darttemplate
index 3018eb11c735f02b75ecb1bb5e370f2b57170cb2..aa1616bb0fec4cd29759538808e28070f5603d9d 100644
--- a/tools/dom/templates/html/impl/impl_MessageEvent.darttemplate
+++ b/tools/dom/templates/html/impl/impl_MessageEvent.darttemplate
@@ -14,30 +14,18 @@ $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS
     if (source == null) {
       source = window;
     }
-$if DART2JS
     if (!Device.isIE) { // TODO: This if check should be removed once IE
       // implements the constructor.
       return JS('MessageEvent', 'new MessageEvent(#, {bubbles: #, cancelable: #, data: #, origin: #, lastEventId: #, source: #, ports: #})',
           type, canBubble, cancelable, data, origin, lastEventId, source,
           messagePorts);
     }
-$endif
     MessageEvent event = document._createEvent("MessageEvent");
     event._initMessageEvent(type, canBubble, cancelable, data, origin,
         lastEventId, source, messagePorts);
     return event;
   }
 
-$if DARTIUM
-  // TODO(alanknight): This really should be generated by the
-  // _OutputConversion in the systemnative.py script, but that doesn't
-  // use those conversions right now, so do this as a one-off.
-  @DomName('MessageEvent.data')
-  @DocsEditable()
-  dynamic get data => convertNativeToDart_SerializedScriptValue(
-      _blink.BlinkMessageEvent.instance.data_Getter_(this));
-
-$else
   // TODO(alanknight): This really should be generated by the
   // _OutputConversion in the systemnative.py script, but that doesn't
   // use those conversions right now, so do this as a one-off.
@@ -52,7 +40,5 @@ $else
   @annotation_Returns_SerializedScriptValue
   final dynamic _get_data;
 
-$endif
-
 $!MEMBERS
 }