[dart:html] rename custom elements callbacks to match spec

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index a3a160895b985c24fab87c46c58108b6397d9357..bb00f1769cfd353a1dcabd840e22c8bbc6957e71 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -9694,15 +9694,39 @@ abstract class Element extends Node implements GlobalEventHandlers, ParentNode,
   /**
    * Called by the DOM when this element has been inserted into the live
    * document.
+   *
+   * More information can be found in the
+   * [Custom Elements](http://w3c.github.io/webcomponents/spec/custom/#dfn-attached-callback)
+   * draft specification.
    */
   @Experimental()
-  void enteredView() {}
+  void attached() {
+    // For the deprecation period, call the old callback.
+    enteredView();
+  }
 
   /**
    * Called by the DOM when this element has been removed from the live
    * document.
+   *
+   * More information can be found in the
+   * [Custom Elements](http://w3c.github.io/webcomponents/spec/custom/#dfn-detached-callback)
+   * draft specification.
    */
   @Experimental()
+  void detached() {
+    // For the deprecation period, call the old callback.
+    leftView();
+  }
+
+  /** *Deprecated*: override [attached] instead. */
+  @Experimental()
+  @deprecated
+  void enteredView() {}
+
+  /** *Deprecated*: override [detached] instead. */
+  @Experimental()
+  @deprecated
   void leftView() {}
 
   /**
@@ -35209,12 +35233,12 @@ _callConstructor(constructor, interceptor) {
   };
 }
 
-_callEnteredView(receiver) {
-  return receiver.enteredView();
+_callAttached(receiver) {
+  return receiver.attached();
 }
 
-_callLeftView(receiver) {
-  return receiver.leftView();
+_callDetached(receiver) {
+  return receiver.detached();
 }
  _callAttributeChanged(receiver, name, oldValue, newValue) {
   return receiver.attributeChanged(name, oldValue, newValue);
@@ -35297,9 +35321,9 @@ void _registerCustomElement(context, document, String tag, Type type,
       JS('=Object', '{value: #}',
           _makeCallbackMethod(_callConstructor(constructor, interceptor))));
   JS('void', '#.attachedCallback = #', properties,
-      JS('=Object', '{value: #}', _makeCallbackMethod(_callEnteredView)));
+      JS('=Object', '{value: #}', _makeCallbackMethod(_callAttached)));
   JS('void', '#.detachedCallback = #', properties,
-      JS('=Object', '{value: #}', _makeCallbackMethod(_callLeftView)));
+      JS('=Object', '{value: #}', _makeCallbackMethod(_callDetached)));
   JS('void', '#.attributeChangedCallback = #', properties,
       JS('=Object', '{value: #}', _makeCallbackMethod3(_callAttributeChanged)));