Only LayoutInline needs to implement addChildIgnoringContinuation().

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 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.
@@ skipping 376 matching lines @@
     bool isLayoutBlock() const final { return true; }
 
     void makeChildrenNonInline(LayoutObject* insertionPoint = nullptr);
 
     virtual void removeLeftoverAnonymousBlock(LayoutBlock* child);
 
     void makeChildrenInlineIfPossible();
 
     void dirtyLinesFromChangedChild(LayoutObject* child) final { m_lineBoxes.dirtyLinesFromChangedChild(LineLayoutItem(this), LineLayoutItem(child)); }
 
-    void addChildIgnoringContinuation(LayoutObject* newChild, LayoutObject* beforeChild) override;
-
     TrackedLayoutBoxListHashSet* positionedObjectsInternal() const;
     TrackedLayoutBoxListHashSet* percentHeightDescendantsInternal() const;
 
     Node* nodeForHitTest() const final;
 
     // Returns true if the positioned movement-only layout succeeded.
     bool tryLayoutDoingPositionedMovementOnly();
 
     bool avoidsFloats() const override { return true; }
 
@@ skipping 81 matching lines @@
     // FIXME: This is temporary as we move code that accesses block flow
     // member variables out of LayoutBlock and into LayoutBlockFlow.
     friend class LayoutBlockFlow;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutBlock, isLayoutBlock());
 
 } // namespace blink
 
 #endif // LayoutBlock_h