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

Source/core/layout/LayoutScrollbarPart.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 
 #include "core/layout/LayoutBlock.h"
 #include "platform/scroll/ScrollTypes.h"
 
 namespace blink {
 
 class LayoutScrollbar;
 
 class LayoutScrollbarPart final : public LayoutBlock {
 public:
-    static LayoutScrollbarPart* createAnonymous(Document*, LayoutScrollbar* = 0, ScrollbarPart = NoPart);
+    static LayoutScrollbarPart* createAnonymous(Document*, LayoutScrollbar* = nullptr, ScrollbarPart = NoPart);
 
     virtual ~LayoutScrollbarPart();
 
     virtual const char* name() const override { return "LayoutScrollbarPart"; }
 
     virtual DeprecatedPaintLayerType layerTypeRequired() const override { return NoDeprecatedPaintLayer; }
 
     virtual void layout() override;
 
     // Scrollbar parts needs to be rendered at device pixel boundaries.
@@ skipping 22 matching lines @@
         ASSERT(isIntegerValue(LayoutBlock::marginRight()));
         return LayoutBlock::marginRight();
     }
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutScrollbarPart || LayoutBlock::isOfType(type); }
     LayoutObject* layoutObjectOwningScrollbar() const;
 
 protected:
     virtual void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
     virtual void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
-    virtual void imageChanged(WrappedImagePtr, const IntRect* = 0) override;
+    virtual void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;
 
 private:
     LayoutScrollbarPart(LayoutScrollbar*, ScrollbarPart);
 
     virtual void computePreferredLogicalWidths() override;
 
     // Have all padding getters return 0. The important point here is to avoid resolving percents
     // against the containing block, since scroll bar corners don't always have one (so it would
     // crash). Scroll bar corners are not actually laid out, and they don't have child content, so
     // what we return here doesn't really matter.
@@ skipping 14 matching lines @@
 
     LayoutScrollbar* m_scrollbar;
     ScrollbarPart m_part;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutScrollbarPart, isLayoutScrollbarPart());
 
 } // namespace blink
 
 #endif // LayoutScrollbarPart_h