[dart:html] rename register to registerElement per spec

tools/dom/templates/html/impl/impl_HTMLDocument.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.
 
 // WARNING: Do not edit - generated code.
 
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
@@ skipping 201 matching lines @@
    * The class being registered must either subclass HtmlElement or SvgElement.
    * If they subclass these directly then they can be used as:
    *
    *     class FooElement extends HtmlElement{
    *        void created() {
    *          print('FooElement created!');
    *        }
    *     }
    *
    *     main() {
-   *       document.register('x-foo', FooElement);
+   *       document.registerElement('x-foo', FooElement);
    *       var myFoo = new Element.tag('x-foo');
    *       // prints 'FooElement created!' to the console.
    *     }
    *
    * The custom element can also be instantiated via HTML using the syntax
    * `<x-foo></x-foo>`
    *
    * Other elements can be subclassed as well:
    *
    *     class BarElement extends InputElement{
    *        void created() {
    *          print('BarElement created!');
    *        }
    *     }
    *
    *     main() {
-   *       document.register('x-bar', BarElement);
+   *       document.registerElement('x-bar', BarElement);
    *       var myBar = new Element.tag('input', 'x-bar');
    *       // prints 'BarElement created!' to the console.
    *     }
    *
    * This custom element can also be instantiated via HTML using the syntax
    * `<input is="x-bar"></input>`
    *
    */
+  void registerElement(String tag, Type customElementClass,
+      {String extendsTag}) {
 $if DART2JS
-  void register(String tag, Type customElementClass, {String extendsTag}) {
     _registerCustomElement(JS('', 'window'), this, tag, customElementClass,
         extendsTag);
+$else
+    _Utils.register(this, tag, customElementClass, extendsTag);
+$endif
   }
-$else
+
+  /** *Deprecated*: use [registerElement] instead. */
+  @deprecated
+  @Experimental()
   void register(String tag, Type customElementClass, {String extendsTag}) {
-    _Utils.register(this, tag, customElementClass, extendsTag);
+    return registerElement(tag, customElementClass, extendsTag: extendsTag);
   }
-$endif
 
   /**
    * Static factory designed to expose `visibilitychange` events to event
    * handlers that are not necessarily instances of [Document].
    *
    * See [EventStreamProvider] for usage information.
    */
   @DomName('Document.visibilityChange')
   @SupportedBrowser(SupportedBrowser.CHROME)
   @SupportedBrowser(SupportedBrowser.FIREFOX)
@@ skipping 38 matching lines @@
   /// parameter must be provided.
   @Experimental()
   ElementUpgrader createElementUpgrader(Type type, {String extendsTag}) {
 $if DART2JS
     return new _JSElementUpgrader(this, type, extendsTag);
 $else
     return new _VMElementUpgrader(this, type, extendsTag);
 $endif
   }
 }