Move Element.focus()/blur() to HTMLElement and SVGElement.

Source/core/html/HTMLElement.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 14 matching lines @@
     [Reflect] attribute DOMString title;
     [Reflect] attribute DOMString lang;
     attribute boolean translate;
     attribute DOMString dir;
     // FIXME: dataset is on Element.
 
     // user interaction
     [Reflect] attribute boolean hidden;
     void click();
     [CustomElementCallbacks] attribute long tabIndex;
-    // FIXME: focus() and blur() are on Element. crbug.com/497274
+    void focus();
+    void blur();
     [Reflect] attribute DOMString accessKey;
     [CustomElementCallbacks] attribute boolean draggable;
     [RuntimeEnabled=ContextMenu] attribute HTMLMenuElement? contextMenu;
     attribute boolean spellcheck;
 
     // HTMLElement implements ElementContentEditable
     // https://html.spec.whatwg.org/#contenteditable
     [CustomElementCallbacks, RaisesException=Setter] attribute DOMString contentEditable;
     readonly attribute boolean isContentEditable;
 
     // CSSOM View Module
     // http://dev.w3.org/csswg/cssom-view/#extensions-to-the-htmlelement-interface
     [PerWorldBindings] readonly attribute Element? offsetParent;
     readonly attribute long offsetTop;
     readonly attribute long offsetLeft;
     readonly attribute long offsetWidth;
     readonly attribute long offsetHeight;
 
     // Non-standard APIs
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementInnerText] attribute DOMString innerText;
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementOuterText] attribute DOMString outerText;
     [Reflect, TreatNullAs=NullString, MeasureAs=PrefixedHTMLElementDropzone] attribute DOMString webkitdropzone;
 };
 
 HTMLElement implements GlobalEventHandlers;