C++11: Replace 0 with nullptr where applicable in layout code.

Source/core/layout/LayoutTableRow.h

 /*
  * Copyright (C) 1997 Martin Jones (mjones@kde.org)
  *           (C) 1997 Torben Weis (weis@kde.org)
  *           (C) 1998 Waldo Bastian (bastian@kde.org)
  *           (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2009, 2013 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
@@ skipping 87 matching lines @@
     virtual const char* name() const override { return "LayoutTableRow"; }
 
 private:
     virtual LayoutObjectChildList* virtualChildren() override { return children(); }
     virtual const LayoutObjectChildList* virtualChildren() const override { return children(); }
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectTableRow || LayoutBox::isOfType(type); }
 
     virtual void willBeRemovedFromTree() override;
 
-    virtual void addChild(LayoutObject* child, LayoutObject* beforeChild = 0) override;
+    virtual void addChild(LayoutObject* child, LayoutObject* beforeChild = nullptr) override;
     virtual void layout() override;
 
     virtual DeprecatedPaintLayerType layerTypeRequired() const override
     {
         if (hasTransformRelatedProperty() || hasHiddenBackface() || hasClipPath() || createsGroup() || style()->shouldCompositeForCurrentAnimations() || style()->hasCompositorProxy())
             return NormalDeprecatedPaintLayer;
 
         if (hasOverflowClip())
             return OverflowClipDeprecatedPaintLayer;
 
         return NoDeprecatedPaintLayer;
     }
 
     virtual void paint(const PaintInfo&, const LayoutPoint&) override;
 
-    virtual void imageChanged(WrappedImagePtr, const IntRect* = 0) override;
+    virtual void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;
 
     virtual void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
 
     void nextSibling() const = delete;
     void previousSibling() const = delete;
 
     LayoutObjectChildList m_children;
     unsigned m_rowIndex : 31;
 };
 
@@ skipping 17 matching lines @@
 
 inline LayoutTableRow* LayoutTableSection::lastRow() const
 {
     ASSERT(children() == virtualChildren());
     return toLayoutTableRow(children()->lastChild());
 }
 
 } // namespace blink
 
 #endif // LayoutTableRow_h