Version 1.5.0-dev.4.14

dart/pkg/web_components/lib/interop.dart

 // Copyright (c) 2014, 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.
 
 /// Provides support for associating a Dart type for Javascript Custom Elements.
 /// This will not work unless `dart_support.js` is loaded.
 library web_components.interop;
 
 import 'dart:async' show Stream, StreamController;
 import 'dart:html' show document, Element;
@@ skipping 13 matching lines @@
     throw new UnsupportedError("Couldn't find "
         "`document._registerDartTypeUpgrader`. Please make sure that "
         "`packages/web_components/dart_support.js` is loaded and available "
         "before calling this function.");
   }
 
   var upgrader = document.createElementUpgrader(
       dartType, extendsTag: extendsTag);
   _doc.callMethod('_registerDartTypeUpgrader', [tagName, upgrader.upgrade]);
 }
+
+/// This function is mainly used to save resources. By default, we save a log of
+/// elements that are created but have no Dart type associated with them. This
+/// is so we can upgrade them as soon as [registerDartType] is invoked. This
+/// function can be called to indicate that we no longer are interested in
+/// logging element creations and that it is sufficient to only upgrade new
+/// elements as they are being created. Typically this is called after the last
+/// call to [registerDartType] or as soon as you know that no element will be
+/// created until the call to [registerDartType] is made.
+void onlyUpgradeNewElements() => _doc.callMethod('_onlyUpgradeNewElements');