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

Source/core/layout/svg/SVGLayoutSupport.h

Index: Source/core/layout/svg/SVGLayoutSupport.h
diff --git a/Source/core/layout/svg/SVGLayoutSupport.h b/Source/core/layout/svg/SVGLayoutSupport.h
index 8ba05271a193417b7890035f732693db1e283292..232605945d7c26c46b50be48e26bbb7e3b7785ba 100644
--- a/Source/core/layout/svg/SVGLayoutSupport.h
+++ b/Source/core/layout/svg/SVGLayoutSupport.h
@@ -74,7 +74,7 @@ public:
     // Important functions used by nearly all SVG layoutObjects centralizing coordinate transformations / paint invalidation rect calculations
     static LayoutRect clippedOverflowRectForPaintInvalidation(const LayoutObject&, const LayoutBoxModelObject* paintInvalidationContainer, const PaintInvalidationState*);
     static const LayoutSVGRoot& mapRectToSVGRootForPaintInvalidation(const LayoutObject&, const FloatRect& localPaintInvalidationRect, LayoutRect&);
-    static void mapLocalToContainer(const LayoutObject*, const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, bool* wasFixed = 0, const PaintInvalidationState* = 0);
+    static void mapLocalToContainer(const LayoutObject*, const LayoutBoxModelObject* paintInvalidationContainer, TransformState&, bool* wasFixed = nullptr, const PaintInvalidationState* = nullptr);
     static const LayoutObject* pushMappingToContainer(const LayoutObject*, const LayoutBoxModelObject* ancestorToStopAt, LayoutGeometryMap&);
 
     // Shared between SVG layoutObjects and resources.