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

Source/core/layout/svg/LayoutSVGModelObject.h

Index: Source/core/layout/svg/LayoutSVGModelObject.h
diff --git a/Source/core/layout/svg/LayoutSVGModelObject.h b/Source/core/layout/svg/LayoutSVGModelObject.h
index 597258618224c42f50723cbb104fb8b32f0bd88d..5cdac3ad7cd0271d1ee710f50ae0484592961e31 100644
--- a/Source/core/layout/svg/LayoutSVGModelObject.h
+++ b/Source/core/layout/svg/LayoutSVGModelObject.h
@@ -47,14 +47,14 @@ public:
 
     virtual bool isChildAllowed(LayoutObject*, const ComputedStyle&) const override;
 
-    virtual LayoutRect clippedOverflowRectForPaintInvalidation(const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState* = 0) const override;
+    virtual LayoutRect clippedOverflowRectForPaintInvalidation(const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState* = nullptr) const override;
 
     virtual FloatRect paintInvalidationRectInLocalCoordinates() const override final { return m_paintInvalidationBoundingBox; }
 
     virtual void absoluteRects(Vector<IntRect>&, const LayoutPoint& accumulatedOffset) const override final;
     virtual void absoluteQuads(Vector<FloatQuad>&, bool* wasFixed) const override;
 
-    virtual void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = 0, const PaintInvalidationState* = 0) const override final;
+    virtual void mapLocalToContainer(const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, MapCoordinatesFlags = ApplyContainerFlip, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr) const override final;
     virtual const LayoutObject* pushMappingToContainer(const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap&) const override final;
     virtual void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;