Implement closed shadow adjustment for Element.offsetParent

third_party/WebKit/Source/core/layout/LayoutObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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
@@ skipping 797 matching lines @@
     // If |ancestor| and |ancestorSkipped| are not null, on return *ancestorSkipped
     // is true if the layoutObject returned is an ancestor of |ancestor|.
     LayoutObject* container(const LayoutBoxModelObject* ancestor = nullptr, bool* ancestorSkipped = nullptr, bool* filterOrReflectionSkipped = nullptr) const;
     // Finds the container as if this object is fixed-position.
     LayoutBlock* containerForFixedPosition(const LayoutBoxModelObject* ancestor = nullptr, bool* ancestorSkipped = nullptr, bool* filterOrReflectionSkipped = nullptr) const;
     // Finds the containing block as if this object is absolute-position.
     LayoutBlock* containingBlockForAbsolutePosition() const;
 
     virtual LayoutObject* hoverAncestor() const { return parent(); }
 
-    Element* offsetParent() const;
+    Element* offsetParent(const Element* = nullptr) const;
 
     void markContainerChainForLayout(bool scheduleRelayout = true, SubtreeLayoutScope* = nullptr);
     void setNeedsLayout(LayoutInvalidationReasonForTracing, MarkingBehavior = MarkContainerChain, SubtreeLayoutScope* = nullptr);
     void setNeedsLayoutAndFullPaintInvalidation(LayoutInvalidationReasonForTracing, MarkingBehavior = MarkContainerChain, SubtreeLayoutScope* = nullptr);
     void clearNeedsLayout();
     void setChildNeedsLayout(MarkingBehavior = MarkContainerChain, SubtreeLayoutScope* = nullptr);
     void setNeedsPositionedMovementLayout();
     void setPreferredLogicalWidthsDirty(MarkingBehavior = MarkContainerChain);
     void clearPreferredLogicalWidthsDirty();
 
@@ skipping 1350 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h