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

Source/core/layout/svg/LayoutSVGInlineText.h

 /*
  * Copyright (C) 2006 Oliver Hunt <ojh16@student.canterbury.ac.nz>
  * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Rob Buis <buis@kde.org>
  *
  * 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 38 matching lines @@
 
 private:
     virtual void setTextInternal(PassRefPtr<StringImpl>) override;
     virtual void styleDidChange(StyleDifference, const ComputedStyle*) override;
 
     virtual FloatRect objectBoundingBox() const override { return floatLinesBoundingBox(); }
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectSVG || type == LayoutObjectSVGInlineText || LayoutText::isOfType(type); }
 
     virtual PositionWithAffinity positionForPoint(const LayoutPoint&) override;
-    virtual LayoutRect localCaretRect(InlineBox*, int caretOffset, LayoutUnit* extraWidthToEndOfLine = 0) override;
+    virtual LayoutRect localCaretRect(InlineBox*, int caretOffset, LayoutUnit* extraWidthToEndOfLine = nullptr) override;
     virtual IntRect linesBoundingBox() const override;
     virtual InlineTextBox* createTextBox(int start, unsigned short length) override;
 
     virtual LayoutRect clippedOverflowRectForPaintInvalidation(const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState*) const override final;
 
     float m_scalingFactor;
     Font m_scaledFont;
     SVGTextLayoutAttributes m_layoutAttributes;
 };
 
@@ skipping 47 matching lines @@
     }
 
     const LayoutSVGInlineText* m_textLayoutObject;
     unsigned m_metricsListOffset;
     unsigned m_characterOffset;
 };
 
 }
 
 #endif // LayoutSVGInlineText_h