Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/core/animation/AnimatableLength.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 38 matching lines @@
         bool isPrimitiveLength = primitiveUnitToNumberType(primitiveValue->primitiveType(), unitType);
         ASSERT_UNUSED(isPrimitiveLength, isPrimitiveLength);
         const double scale = CSSPrimitiveValue::conversionToCanonicalUnitsScaleFactor(primitiveValue->primitiveType());
         return create(primitiveValue->getDoubleValue() * scale, unitType, primitiveValue);
     }
 
     if (value->isCalcValue())
         return create(toCSSCalcValue(value)->expressionNode());
 
     ASSERT_NOT_REACHED();
-    return 0;
+    return nullptr;
 }
 
 bool AnimatableLength::canCreateFrom(const CSSValue* value)
 {
     ASSERT(value);
     if (value->isPrimitiveValue()) {
         const CSSPrimitiveValue* primitiveValue = WebCore::toCSSPrimitiveValue(value);
         if (primitiveValue->cssCalcValue())
             return true;
 
@@ skipping 169 matching lines @@
     case UnitTypeViewportMax:
         return CSSPrimitiveValue::CSS_VMAX;
     case UnitTypeCalc:
         return CSSPrimitiveValue::CSS_UNKNOWN;
     }
     ASSERT_NOT_REACHED();
     return CSSPrimitiveValue::CSS_UNKNOWN;
 }
 
 } // namespace WebCore