Move collapseAnonymousBlockChild() to LayoutBlockFlow, and make it non-static.

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

 /*
  * Copyright (C) 2005 Apple Computer
  *
  * 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
@@ skipping 20 matching lines @@
 // to date as the button changes.
 class LayoutButton final : public LayoutFlexibleBox {
 public:
     explicit LayoutButton(Element*);
     ~LayoutButton() override;
 
     const char* name() const override { return "LayoutButton"; }
     bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutButton || LayoutFlexibleBox::isOfType(type); }
 
     bool canBeSelectionLeaf() const override { return node() && node()->hasEditableStyle(); }
-    bool canCollapseAnonymousBlockChild() const override { return true; }
 
     void addChild(LayoutObject* newChild, LayoutObject *beforeChild = nullptr) override;
     void removeChild(LayoutObject*) override;
     void removeLeftoverAnonymousBlock(LayoutBlock*) override { }
     bool createsAnonymousWrapper() const override { return true; }
 
     bool hasControlClip() const override;
     LayoutRect controlClipRect(const LayoutPoint&) const override;
 
     int baselinePosition(FontBaseline, bool firstLine, LineDirectionMode, LinePositionMode) const override;
 
 private:
     void updateAnonymousChildStyle(const LayoutObject& child, ComputedStyle& childStyle) const override;
 
     bool hasLineIfEmpty() const override { return isHTMLInputElement(node()); }
 
     LayoutBlock* m_inner;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutButton, isLayoutButton());
 
 } // namespace blink
 
 #endif // LayoutButton_h