Fixing issues from lifecycle events CL

pkg/custom_element/lib/custom_element.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.
 
 /**
  * Custom DOM elements.
  *
  * This library provides access to the Polymer project's
  * [Custom Elements]
  * (http://www.polymer-project.org/platform/custom-elements.html)
@@ skipping 156 matching lines @@
   getShadowRoot(String componentName) => _generatedRoots[componentName];
 
   /**
    * Invoked when this component gets created.
    * Note that [root] will be a [ShadowRoot] if the browser supports Shadow DOM.
    */
   void created() {}
 
   /** Invoked when this component gets inserted in the DOM tree. */
   void inserted() {}
+  @deprecated
+  void enteredView() {}
 
   /** Invoked when this component is removed from the DOM tree. */
   void removed() {}
+  @deprecated
+  void leftView() {}
 
   // TODO(jmesserly): how do we implement this efficiently?
   // See https://github.com/dart-lang/web-ui/issues/37
   /** Invoked when any attribute of the component is modified. */
   void attributeChanged(String name, String oldValue, String newValue) {}
 
   get model => host.model;
 
   void set model(newModel) {
     host.model = newModel;
@@ skipping 449 matching lines @@
       for (var removed in record.removedNodes) {
         if (identical(node, removed)) {
           observer.disconnect();
           element.removed();
           return;
         }
       }
     }
   }).observe(element.parentNode, childList: true);
 }