Add dataset property to SVGElement interface.

third_party/WebKit/Source/core/svg/SVGElement.idl

 /*
  * Copyright (C) 2004, 2005 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  * Copyright (C) 2006 Apple Inc. All rights reserved.
  *
  * 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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 // http://www.w3.org/TR/SVG2/types.html#InterfaceSVGElement
 
 interface SVGElement : Element {
     [MeasureAs=SVGClassName] readonly attribute SVGAnimatedString className;
+    [SameObject, PerWorldBindings] readonly attribute DOMStringMap dataset;
     // CSS Object Model (CSSOM)
     // http://dev.w3.org/csswg/cssom/#the-elementcssinlinestyle-interface
     [SameObject, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
 
     readonly attribute SVGSVGElement? ownerSVGElement;
     readonly attribute SVGElement? viewportElement;
     [CustomElementCallbacks] attribute long tabIndex;
     void focus();
     void blur();
 };
 
 SVGElement implements GlobalEventHandlers;