[dart:html] rename register to registerElement per spec

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

 // Copyright (c) 2012, 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.
 
 part of $LIBRARYNAME;
 
 class _ChildrenElementList extends ListBase<Element>
     implements NodeListWrapper {
   // Raw Element.
   final Element _element;
@@ skipping 343 matching lines @@
    * created. It can only be invoked by subclasses of Element from
    * that classes created constructor.
    *
    *     class CustomElement extends Element {
    *       factory CustomElement() => new Element.tag('x-custom');
    *
    *       CustomElement.created() : super.created() {
    *          // Perform any element initialization.
    *       }
    *     }
-   *     document.register('x-custom', CustomElement);
+   *     document.registerElement('x-custom', CustomElement);
    */
   Element.created() : super._created() {
     // Validate that this is a custom element & perform any additional
     // initialization.
     _initializeCustomElement(this);
   }
 
   /**
    * Creates the HTML element specified by the tag name.
    *
@@ skipping 988 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }