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

Source/core/layout/LayoutTextControl.h

 /*
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.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,
@@ skipping 62 matching lines @@
     virtual int inlineBlockBaseline(LineDirectionMode direction) const override { return lastLineBoxBaseline(direction); }
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectTextControl || LayoutBlockFlow::isOfType(type); }
 
 private:
     virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const override final;
     virtual void computePreferredLogicalWidths() override final;
     virtual void removeLeftoverAnonymousBlock(LayoutBlock*) override final { }
     virtual bool avoidsFloats() const override final { return true; }
 
-    virtual void addChild(LayoutObject* newChild, LayoutObject* beforeChild = 0) override final;
+    virtual void addChild(LayoutObject* newChild, LayoutObject* beforeChild = nullptr) override final;
 
     virtual void addFocusRingRects(Vector<LayoutRect>&, const LayoutPoint& additionalOffset) const override final;
 
     virtual bool canBeProgramaticallyScrolled() const override final { return true; }
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutTextControl, isTextControl());
 
 // LayoutObject for our inner container, for <search> and others.
 // We can't use LayoutFlexibleBox directly, because flexboxes have a different
@@ skipping 11 matching lines @@
         return LayoutBlock::baselinePosition(baseline, firstLine, direction, position);
     }
     virtual int firstLineBoxBaseline() const override { return LayoutBlock::firstLineBoxBaseline(); }
     virtual int inlineBlockBaseline(LineDirectionMode direction) const override { return lastLineBoxBaseline(direction); }
 };
 
 
 } // namespace blink
 
 #endif // LayoutTextControl_h