Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/css/resolver/StyleBuilderCustom.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
@@ skipping 671 matching lines @@
     NinePieceImage image;
     state.styleMap().mapNinePieceImage(state.style(), CSSPropertyWebkitBorderImage, value, image);
     state.style()->setBorderImage(image);
 }
 
 void StyleBuilderFunctions::applyValueCSSPropertyWebkitClipPath(StyleResolverState& state, CSSValue* value)
 {
     if (value->isPrimitiveValue()) {
         CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
         if (primitiveValue->getValueID() == CSSValueNone) {
-            state.style()->setClipPath(0);
+            state.style()->setClipPath(nullptr);
         } else if (primitiveValue->isShape()) {
             state.style()->setClipPath(ShapeClipPathOperation::create(basicShapeForValue(state, primitiveValue->getShapeValue())));
         } else if (primitiveValue->primitiveType() == CSSPrimitiveValue::CSS_URI) {
             String cssURLValue = primitiveValue->getStringValue();
             KURL url = state.document().completeURL(cssURLValue);
             // FIXME: It doesn't work with forward or external SVG references (see https://bugs.webkit.org/show_bug.cgi?id=90405)
             state.style()->setClipPath(ReferenceClipPathOperation::create(cssURLValue, AtomicString(url.fragmentIdentifier())));
         }
     }
 }
@@ skipping 1468 matching lines @@
         break;
     }
     case CSSPropertyEnableBackground:
         // Silently ignoring this property for now
         // http://bugs.webkit.org/show_bug.cgi?id=6022
         break;
     }
 }
 
 } // namespace WebCore