Document the tracking bugs of some IDL FIXMEs

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,
  * 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.
  */
 
 // https://html.spec.whatwg.org/#htmlelement
 
 interface HTMLElement : Element {
     // metadata attributes
     [Reflect] attribute DOMString title;
     [Reflect] attribute DOMString lang;
     attribute boolean translate;
     attribute DOMString dir;
-    // FIXME: dataset is on Element.
+    // FIXME: dataset is on Element. crbug.com/498485
 
     // user interaction
     [Reflect] attribute boolean hidden;
     void click();
     [CustomElementCallbacks] attribute long tabIndex;
     void focus();
     void blur();
     [Reflect] attribute DOMString accessKey;
     [CustomElementCallbacks] attribute boolean draggable;
     [RuntimeEnabled=ContextMenu] attribute HTMLMenuElement? contextMenu;
@@ skipping 17 matching lines @@
     // FIXME: style should have [PutForwards=cssText].
     [SameObject, PerWorldBindings] readonly attribute CSSStyleDeclaration style;
 
     // 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;