Implement closed shadow adjustment for Element.offsetParent

third_party/WebKit/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,
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     [CEReactions, RuntimeEnabled=ContextMenu] attribute HTMLMenuElement? contextMenu;
     [CEReactions] attribute boolean spellcheck;
 
     // HTMLElement implements ElementContentEditable
     // https://html.spec.whatwg.org/#contenteditable
     [CEReactions, 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;
+    [PerWorldBindings, ImplementedAs=unclosedOffsetParent] readonly attribute Element? offsetParent;
+    [ImplementedAs=offsetTopForBinding] readonly attribute long offsetTop;
+    [ImplementedAs=offsetLeftForBinding] readonly attribute long offsetLeft;
+    [ImplementedAs=offsetWidthForBinding] readonly attribute long offsetWidth;
+    [ImplementedAs=offsetHeightForBinding] readonly attribute long offsetHeight;
 
     // CSS Object Model (CSSOM)
     // http://dev.w3.org/csswg/cssom/#the-elementcssinlinestyle-interface
     [SameObject, PerWorldBindings, PutForwards=cssText] readonly attribute CSSStyleDeclaration style;
     // Typed OM
     // https://drafts.css-houdini.org/css-typed-om/#inline-stylepropertymap-objects
     [RuntimeEnabled=CSSTypedOM] readonly attribute StylePropertyMap styleMap;
 
     // Non-standard APIs
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementInnerText] attribute DOMString innerText;
     [TreatNullAs=NullString, CustomElementCallbacks, RaisesException=Setter, MeasureAs=HTMLElementOuterText] attribute DOMString outerText;
     [CEReactions, Reflect, TreatNullAs=NullString, MeasureAs=PrefixedHTMLElementDropzone] attribute DOMString webkitdropzone;
 };
 
 HTMLElement implements GlobalEventHandlers;